What is the best AI email assistant for Gmail and Outlook?

Kerna takes first place in our editorial ranking for small teams handling customer and supplier email. It combines custom categories, reusable document fields, summaries and reply drafting in 45 languages. The ranking reflects this workflow rather than a universal benchmark.

Which tools work with my existing email account?

The listed tools use add-ons, native features or connected-account services. Check the supported provider, account type and client. A different email app does not necessarily require moving the mailbox to a new provider.

How can I check whether my email data stays in the EU?

Check application hosting, model-processing regions, retention and subprocessors separately. Kerna’s application runs in Belgium with Firestore in Poland. A contract with an EU entity or zero-retention terms alone does not prove EU-only model processing. Consult the current privacy and subprocessor documentation.

What does personal-data masking mean?

Masking removes or replaces detected personal details before model processing. Kerna uses this step across plans. It reduces exposure but should not be described as guaranteed anonymisation of every message. Retention, encryption and model-training rules are separate safeguards.

How much does an AI email assistant cost for a small team?

Compare the required features for the same users or mailboxes and billing period. Kerna Business costs EUR 69 per month for up to five users sharing 7,500,000 tokens. Existing suite AI may have no additional licence fee; new tools and upgrades should be compared on incremental cost and useful output.

Does Kerna send email on my behalf?

No. Kerna prepares drafts when requested. You review, edit and send them yourself.

Why are some email apps not included in the ranking?

The ranking focuses on assistance alongside existing Gmail and Outlook workflows. Other email clients, agent platforms and shared-workspace products may suit different needs; their exclusion is a scope choice, not a claim that they are inferior.

Where do the prices and scores come from?

Prices come from vendor materials, with billing terms stated. Scores are Kerna’s editorial judgement for the workflow described in the rubric, not independent performance measurements. Unverified current amounts are identified rather than presented as confirmed prices.

Comparison

The best AI email assistants for Gmail and Outlook

10 AI email tools compared for customer and supplier correspondence, document handling and small-team use. In this Kerna editorial ranking, Kerna takes first place with 29 out of 30.

Get Kerna for Gmail Get Kerna for Outlook

The short version

The main differences for everyday business email.

Kerna, 29 of 30. Our first choice for customer and supplier email: custom categories, attachment fields and export, 45 languages, and add-ons for Gmail and Outlook. Business costs EUR 69 per month for up to five users sharing a token allowance.
Already paying for the suite? Your existing plan may already include useful AI features. Compare those with Kerna on the tasks you repeat: classifying incoming requests, selecting document fields and exporting checked results. Availability depends on your licence and configuration.
Compare the cost for your team. Vendors charge by user, mailbox or plan. Kerna Business covers up to five users for EUR 69 per month, within a shared token allowance. Compare the required features, billing period and usage limits as well as the headline price.

How we score these tools

Six criteria, up to five points each, 30 in total. These are Kerna editorial fit scores for small teams handling customer and supplier email, not independent benchmarks or security audit results. We prioritise custom categories, reusable document fields, data minimisation and practical deployment.

Data minimisation and transparency

Fit with a small team’s need to limit message exposure and understand retention, subprocessors and available controls. This is not a security certification score.

5.: Documented masking before model processing, zero message-content retention and clear processing terms across entry and team plans.
4.: Strong documented processing controls or a design that limits content access, with some scope or configuration differences from our preferred workflow.
3.: Published safeguards, with relevant retention choices, model-input handling or small-team availability still requiring clarification.
2.: Limited detail for the assessed AI workflow; several important processing questions remain open.
1.: Insufficient documented information to assess the workflow. This does not establish that safeguards are absent.

Incoming email and documents

Fit for understanding and organising incoming work, including categories, summaries, document fields and automation.

5.: Extensive support for incoming work through either reusable category and extraction settings or a developed automatic organisation workflow.
4.: Strong organisation or automation, with additional tools or checks needed for some document tasks.
3.: Useful summaries, prioritisation or organisation, with a less direct fit for the complete category-to-export workflow.
2.: A narrow set of incoming-email tasks is supported.
1.: Little documented support for organising or understanding incoming work.

Writing and replies

Drafting, rewriting and adapting messages to the recipient, purpose and language.

5.: Broad drafting and rewriting support with practical ways to guide style, purpose or language.
4.: Strong drafting with personalisation or editing; some workflow details depend on prompts or configuration.
3.: Useful reply drafting centred on a particular workflow, with less documented support for the full writing process.
2.: Basic assistance with replies or selected text.
1.: Generative writing is outside the assessed product’s main scope.

Language support

Published support for the languages used in business correspondence. Coverage is not a substitute for testing writing quality.

5.: Broad documented multilingual support; check the feature-specific language availability.
4.: Multilingual writing with language controls, although coverage can vary by feature.
3.: Multilingual use is described, but the reviewed material gives less feature-specific detail.
2.: Language coverage needs testing or the product primarily performs language-independent organisation.
1.: Documented support is too limited for the assessed multilingual workflow.

Deployment and administration

Installation, supported accounts and clients, team management and fit for existing Gmail or Outlook workflows.

5.: Native suite integration with central administration and identity management.
4.: Straightforward connection or installation with useful team options; some controls or clients have limitations.
3.: Practical deployment with a narrower platform scope or advanced administration reserved for a separate tier.
2.: Material configuration work is required for the assessed team.
1.: Specialist setup and ongoing infrastructure management are required.

Value for a five-person team

Editorial value assessment combining the relevant price, included tasks, limits and billing unit. We do not rank different currencies by their face value.

5.: Strong fit for the assessed workflow, a predictable team package and a useful free plan for testing its core functions.
4.: Competitive cost for the relevant tasks or useful AI already included in an existing subscription.
3.: Reasonable value, but the relevant tier, account count or billing commitment needs careful comparison.
2.: A larger paid package or higher team spend may be difficult to justify for this specific email workflow.
1.: Substantial cost or setup overhead relative to the narrow workflow assessed here.

Scorecard

Tool	Data minimisation and transparency	Incoming email and documents	Writing and replies	Language support	Deployment and administration	Value for a five-person team	Total
Kerna	5	5	5	5	4	5	29/30
Microsoft 365 Copilot in Outlook	4	4	5	5	5	2	25/30
Gemini in Gmail	4	3	4	5	5	4	25/30
MailMaestro	3	4	5	4	3	4	23/30
Virtualworkforce.ai	3	4	4	5	4	3	23/30
Fyxer AI	3	5	4	3	4	2	21/30
Mailbutler	3	3	4	3	4	3	20/30
Gmelius	4	4	3	3	3	3	20/30
SaneBox	4	4	1	2	4	4	19/30
Inbox Zero	3	4	3	2	3	3	18/30

Kerna ranks first for the workflow defined above. Its combination of custom categories, attachment extraction and language support is particularly relevant to our target users. Scores express editorial judgement based on documented features; they do not establish universal product quality. Read each rationale and check the features needed for your own work.

What each one actually does

Tool	Triage	Thread summary	Attachment fields	Reply drafting	Translation	Personal-data masking before AI
Kerna	✓	✓	✓	✓	✓	✓
Microsoft 365 Copilot in Outlook	Partial	✓	?	✓	Partial	—
Gemini in Gmail	—	✓	?	✓	Partial	—
MailMaestro	Partial	✓	Partial	✓	Partial	?
Virtualworkforce.ai	Partial	?	?	✓	✓	?
Fyxer AI	✓	✓	Partial	✓	?	—
Mailbutler	Partial	✓	—	✓	?	—
Gmelius	✓	?	—	✓	?	—
SaneBox	✓	—	—	—	—	?
Inbox Zero	✓	?	—	✓	?	—

A tick indicates a documented capability. Partial means the published scope differs from the task assessed here. A dash means the capability is not confirmed for the assessed plan and workflow; it is not proof that the vendor cannot offer it. A question mark means the available documentation is insufficient.

What a five-person team pays

Compare the same number of users or mailboxes and the same billing period. For software already included in your suite, count the additional cost rather than charging the existing subscription twice. Check token limits, feature tiers and any required base licences.

Tool	Free tier	Entry plan for the assessed features	Cost for five users
Kerna	Yes. Starter includes all functions within its token allowance.	Standard: EUR 12 per month. Pro: EUR 22 per month. Free Starter available.1	Business: EUR 69 per month for up to five users sharing 7,500,000 tokens.1
Microsoft 365 Copilot in Outlook	Copilot Chat is included with eligible licences. Its access and capabilities differ from the paid Copilot experience.	Copilot Business: USD 21 per user/month equivalent with annual payment; the checked US page advertises USD 18 under promotional terms. An eligible Microsoft 365 plan is required.4	Five Business add-ons: USD 1,260/year (USD 105/month equivalent), or USD 1,080/year at the advertised USD 18 promotion. Base Microsoft 365 licences are additional if not already held.4
Gemini in Gmail	Workspace offers a 14-day business trial. Personal Gmail and Google AI offers have separate eligibility and limits.	Gemini in Gmail is included in Workspace Business Starter, Standard and Plus. Workspace pricing varies by region and billing term.7	No separate AI surcharge for five users already on an eligible Workspace plan. New customers must include the underlying Workspace subscription.7
MailMaestro	Yes. After a 14-day trial, Free permits three compose, reply or improve requests per week.	Professional/Team: USD 15/user/month or USD 144/user/year, equivalent to USD 12/month.9	USD 75/month or USD 720/year for five Professional/Team users; annual equivalent USD 60/month.9
Virtualworkforce.ai	Yes: one AI agent, one user and one million tokens per month. No shared mailboxes, document processing or admin dashboard in Free.	Annual USD rates per mailbox/month equivalent: Professional 19, Growth 34, Team 69. Monthly rates: 29, 45 and 89 respectively. Minimum mailbox counts and feature tiers apply.11	Five separate mailboxes on Growth: USD 225/month or USD 2,040/year. Shared mailboxes require Growth or higher; confirm the applicable minimum and quote for a shared-address team.11
Fyxer AI	No permanent free plan is listed. Standard trials last seven days; Enterprise trial arrangements can be discussed with sales.	Starter: USD 30/user/month, or USD 270/user/year. Professional: USD 50/user/month, or USD 450/user/year.12	Starter: USD 150/month or USD 1,350/year for five. Professional: USD 250/month or USD 2,250/year for five.12
Mailbutler	Free Starter with limited features; a separate 14-day trial includes all features.	Smart with AI: USD 14/user/month or USD 132/user/year, equivalent to USD 11/month. EUR pricing is also available.14	Smart: USD 70/month or USD 660/year for five users; annual equivalent USD 55/month.14
Gmelius	No permanent free plan is listed. A seven-day trial is advertised.	Meli: USD 21/user/month or USD 228/user/year. Growth: USD 33/user/month or USD 300/user/year.16	Five Meli users: USD 105/month or USD 1,140/year. Five Growth users: USD 165/month or USD 1,500/year.16
SaneBox	Check the current trial terms directly with SaneBox; do not treat a trial as a permanent free plan.	Check the current Snack, Lunch and Dinner offers by account count and billing term; no current numerical price was verified in this review.19	Calculate five subscriptions using the same current billing term, or request a business quote. A verified current five-user amount is not available here.20
Inbox Zero	A seven-day trial is advertised; no permanent free hosted plan is listed.	Displayed annual rates: Starter USD 20/user/month equivalent; Plus USD 35; Professional USD 50. Monthly-payment terms differ.22	Annual billing for five: Starter USD 1,200/year; Plus USD 2,100/year; Professional USD 3,000/year.22

Currencies are not converted. Annual-plan monthly equivalents are not monthly-payment offers. Prices exclude any existing email subscription unless explicitly stated; taxes and regional offers may differ.

All 10 tools in this ranking

Number one

1. Kerna29 / 30

Kerna sp. z o.o., Katowice, Poland · Gmail add-on and Outlook add-in

Kerna brings custom inbox categories, thread summaries, attachment extraction and reply drafting to Gmail and Outlook. It supports 45 languages and runs each task when you request it. A practical choice for customer enquiries, order changes and supplier documents.

Data handling. The application runs on Google Cloud Run in Belgium, with Firestore in Poland. Kerna masks detected personal data before model processing and has a zero data retention agreement with OpenAI Ireland Limited. Account and usage data have separate retention rules. The model-processing location must be established from the applicable configuration and terms, not the contracting entity’s address.3

Price. Standard: EUR 12 per month. Pro: EUR 22 per month. Free Starter available.1

Before you install. Check the supported Outlook account and client. Outlook mobile is not supported; the Gmail add-on also works in the Gmail mobile app. Sign-in uses Microsoft or Google accounts; configurable enterprise SSO and SCIM are not offered.

Score rationale

Data minimisation and transparency 5/5.: Masking before model processing, zero message-content retention and published processing terms underpin the strong fit with our data-minimisation criterion.
Incoming email and documents 5/5.: Custom categories, thread summaries and reusable attachment fields, with export to spreadsheets or documents.
Writing and replies 5/5.: Replies with a choice of tone and purpose, writing from a brief and translation. Users review and send messages themselves.
Language support 5/5.: 45 supported languages. Evaluate terminology and style on examples from your own correspondence.
Deployment and administration 4/5.: Official Gmail and Outlook add-ons, administrator deployment and shared team usage. No configurable enterprise SSO or SCIM.
Value for a five-person team 5/5.: Business costs EUR 69 per month for up to five users, with 7,500,000 shared tokens. A supported email account is still required; the plan is not unlimited.

Get Kerna for Gmail Get Kerna for Outlook

2. Microsoft 365 Copilot in Outlook25 / 30

Microsoft Corporation, United States · Outlook

Microsoft’s integrated assistant for Outlook and other Microsoft 365 apps. It supports summaries, writing and work with organisational content, depending on licence and configuration.

Processing. Microsoft publishes enterprise data protection and access controls for Copilot. Data-boundary coverage, model providers and exceptions depend on the applicable service and configuration. The reviewed overview does not establish universal masking of personal data before model processing.5

Price. Copilot Business: USD 21 per user/month equivalent with annual payment; the checked US page advertises USD 18 under promotional terms. An eligible Microsoft 365 plan is required.4

What to consider. Distinguish included Copilot Chat from paid Copilot licences. Compare incremental cost if Microsoft 365 is already paid for. The assessed integration is Outlook, not a Gmail add-on.

Score rationale

Data minimisation and transparency 4/5.: Documented enterprise protections; check the applicable model, region and data-handling terms. Company headquarters alone is not a security measure.
Incoming email and documents 4/5.: Summaries and organisation support. Copilot can create and edit Outlook rules, including categorisation; this is broader than priority ranking alone.
Writing and replies 5/5.: Drafting and rewriting with instructions to guide the result. Available features depend on the licence.
Language support 5/5.: Broad multilingual support; check the language list for the specific Outlook feature.
Deployment and administration 5/5.: Native Microsoft 365 integration with central administration.
Value for a five-person team 2/5.: Paid suite-wide AI can cost more than a small team needs for email alone. Included Chat may have no incremental licence cost.

Kerna vs Microsoft 365 Copilot in Outlook: detailed comparison

3. Gemini in Gmail25 / 30

Google LLC, United States · Gmail

Gemini in Gmail helps summarise conversations, draft messages and find information in mail and Google Drive. Availability varies by account, plan, feature and language.

Processing. Google states that Workspace data is not reviewed by humans or used to train generative models outside the customer’s domain without permission. Regional and administrative controls depend on the service and plan. This does not by itself establish masking before model processing.8

Price. Gemini in Gmail is included in Workspace Business Starter, Standard and Plus. Workspace pricing varies by region and billing term.7

What to consider. This entry assesses Gemini in Gmail, not every Gemini app or integration. Test your category-to-export workflow rather than assuming either that a general assistant can do everything or that it cannot extract document information.

Score rationale

Data minimisation and transparency 4/5.: Published business-data protections and administrative controls. Check regional settings and retention separately.
Incoming email and documents 3/5.: Summaries, search and questions about mail. A reusable category and document-export workflow needs direct comparison with Kerna.
Writing and replies 4/5.: Drafting and rewriting can be guided by instructions, including style and tone; controls vary by feature.
Language support 5/5.: Broad multilingual support, with feature-specific availability.
Deployment and administration 5/5.: Integrated into Gmail and managed through Workspace administration for business accounts.
Value for a five-person team 4/5.: No extra AI fee for Gemini in Gmail when included in the existing Workspace plan. Assess Kerna’s additional workflow value separately.

Kerna vs Gemini in Gmail: detailed comparison

4. MailMaestro23 / 30

Maestro Labs PTE. LTD., Singapore · Outlook add-in, Gmail (Chrome extension)

MailMaestro supports writing, replies, editing and email organisation. Professional/Team includes email and attachment summaries; Gmail uses a Chrome extension and Outlook a marketplace add-in.

Processing. Maestro Labs publishes SOC 2 Type II, CASA Tier 2 and Microsoft Attestation information. It states that data is not used to train AI models and is encrypted in transit and at rest. Retention is limited to service needs; zero-day retention is available to Enterprise customers.10

Price. Professional/Team: USD 15/user/month or USD 144/user/year, equivalent to USD 12/month.9

What to consider. Check feature availability by platform. SSO and custom retention are listed under Enterprise. Do not infer that lower plans lack GDPR obligations or all audited safeguards merely because security is highlighted in Enterprise.

Score rationale

Data minimisation and transparency 3/5.: Documented safeguards. The small-team comparison should focus on retention options and model-input handling, not claim that basic security is absent.
Incoming email and documents 4/5.: Automatic labels and paid thread and attachment summaries. Reusable field extraction and export are not established by the reviewed pricing page.
Writing and replies 5/5.: Writing, replies, editing and templates. Company-wide templates and tones are listed under Enterprise.
Language support 4/5.: Multilingual writing; confirm availability for the required feature and language.
Deployment and administration 3/5.: Outlook add-in and Gmail Chrome extension; the extension does not run inside the Gmail mobile app.
Value for a five-person team 4/5.: Five Professional/Team users cost USD 75/month or USD 720/year. A 14-day trial precedes the limited free plan.

Kerna vs MailMaestro: detailed comparison

5. Virtualworkforce.ai23 / 30

Virtualworkforce.ai — legal entity not published on the pages checked · Gmail, Outlook, Shared inboxes (Growth tier and above)

Virtualworkforce.ai combines email drafting, labelling and forwarding with connected business data, including ERP and CRM integrations. It is priced per AI agent, meaning mailbox.

Processing. The vendor publishes security commitments and links to a trust centre. Review the DPA, subprocessors, retention and integration permissions for the proposed deployment. The pricing page alone does not establish model-input masking or processing locations.11

Price. Annual USD rates per mailbox/month equivalent: Professional 19, Growth 34, Team 69. Monthly rates: 29, 45 and 89 respectively. Minimum mailbox counts and feature tiers apply.11

What to consider. Shared mailboxes start at Growth; document processing is listed under Team. Professional permits five users but does not include shared mailboxes. The relevant package depends on mailbox count and required integrations.

Score rationale

Data minimisation and transparency 3/5.: Assess the processing chain and connected systems using the trust documentation; missing detail on a pricing page is not evidence of missing safeguards.
Incoming email and documents 4/5.: Labelling and forwarding across plans; document processing and deep inbox analysis are listed under Team.
Writing and replies 4/5.: Drafting supported by business data and connected sources.
Language support 5/5.: The pricing matrix lists support for 59 languages.
Deployment and administration 4/5.: Integration options include ERP, CRM and other sources. Shared mailboxes and the administration dashboard start at Growth.
Value for a five-person team 3/5.: Five separate mailboxes fit Growth: USD 170/month equivalent annually. A five-user allowance in Professional must not be presented as shared-mailbox support.

6. Fyxer AI21 / 30

Fyxer AI Limited, United Kingdom (company 15189973) · Gmail, Outlook

Fyxer organises Gmail and Outlook mail, prepares reply drafts and offers meeting notes. Its main workflow runs automatically.

Processing. Fyxer publishes SOC 2 Type II and ISO 27001 assurances, states that customer data does not train third-party AI models, and describes least-privilege support access. Its trust centre provides further documents. The reviewed security page does not confirm universal masking before model processing.13

Price. Starter: USD 30/user/month, or USD 270/user/year. Professional: USD 50/user/month, or USD 450/user/year.12

What to consider. Starter covers one inbox. Professional adds multiple inboxes and more features. SSO and SCIM are listed under Enterprise; the FAQ states a 50-user minimum with scope for discussing nearby requirements.

Score rationale

Data minimisation and transparency 3/5.: Published security assurances; clarify retention and model-input handling for the chosen plan.
Incoming email and documents 5/5.: Developed automatic categorisation with user corrections and folder preferences. This score reflects organisation, not confirmed structured field export.
Writing and replies 4/5.: Drafts tailored to the user’s writing style, ready for review. The vendor states it does not send emails on the user’s behalf.
Language support 3/5.: Test the required languages and terminology; the reviewed pricing page does not give a complete feature-by-language matrix.
Deployment and administration 4/5.: Gmail and Outlook connections; some identity controls require Enterprise.
Value for a five-person team 2/5.: Five Starter users cost USD 150 with monthly billing, or USD 112.50/month equivalent annually. Compare like-for-like billing and currencies.

Kerna vs Fyxer AI: detailed comparison

7. Mailbutler20 / 30

Mailbutler GmbH, Germany · Gmail, Outlook, Apple Mail

Mailbutler combines tracking, templates, signatures and collaboration with AI writing and summaries in its Smart plan.

Processing. Mailbutler’s privacy policy distinguishes AI processing from tracking and scheduled sending, and states that Google Workspace API data is not used to train general-purpose AI models. Check the Smart Assistant terms for model-provider handling and the scope of metadata retention.15

Price. Smart with AI: USD 14/user/month or USD 132/user/year, equivalent to USD 11/month. EUR pricing is also available.14

What to consider. Select the plan that includes AI. Follow-up urgency is not the whole organisation feature set: Mailbutler also lists tags and automation. A reusable attachment-field export workflow is not confirmed by the reviewed pricing page.

Score rationale

Data minimisation and transparency 3/5.: Published feature-specific privacy terms. Check retention and masking separately; EU incorporation does not prove every processing location.
Incoming email and documents 3/5.: Summaries, tags, automation and follow-up prioritisation. The fit with repeated document-field extraction needs testing.
Writing and replies 4/5.: AI composition and editing supported by templates and mail merge.
Language support 3/5.: Check the required languages directly; the reviewed pricing page is not a language-support specification.
Deployment and administration 4/5.: Email integrations and collaboration features; verify the supported client version and team settings.
Value for a five-person team 3/5.: Smart costs USD 70/month for five or USD 660/year. Compare the AI tier, not the lower tracking-only entry offer.

8. Gmelius20 / 30

Gmelius SA, Switzerland · Gmail

Gmelius offers AI assistance in Gmail, with shared inboxes, assignments and automation in its collaboration plans.

Processing. Gmelius’s published legal security page describes encryption, Google Cloud infrastructure and OAuth permissions that include sending and managing mail. It distinguishes email content from stored configuration and tracking metadata. Consult its current trust documentation for the scope of each AI feature.18

Price. Meli: USD 21/user/month or USD 228/user/year. Growth: USD 33/user/month or USD 300/user/year.16

What to consider. Meli is an individual AI plan. Shared inboxes and automation rules start at Growth, so use that price when assessing collaboration. This comparison concerns its Gmail workflow.

Score rationale

Data minimisation and transparency 4/5.: Published processing and access terms. A Swiss company address alone does not locate the processing infrastructure.
Incoming email and documents 4/5.: AI organisation and team automation, with shared inbox workflows from Growth.
Writing and replies 3/5.: AI drafting within individual and team email workflows; test the required tone and response types.
Language support 3/5.: Confirm language support for the selected assistant and task.
Deployment and administration 3/5.: Strong Gmail team features; a narrower fit for organisations that also need an Outlook workflow.
Value for a five-person team 3/5.: Five Meli users cost USD 105/month or USD 1,140/year. Shared inboxes require Growth, which costs more.

9. SaneBox19 / 30

SaneBox, Inc., United States · Any client, server side

SaneBox organises mail through the connected account, helping separate messages that need attention from those that can wait. It focuses on inbox management rather than the full writing and document-extraction workflow assessed here.

Processing. SaneBox states that prioritisation uses message headers and behavioural patterns. Optional functions may retrieve message bodies, which it says are not stored. It describes encrypted credentials and controlled infrastructure access.21

Price. Check the current Snack, Lunch and Dinner offers by account count and billing term; no current numerical price was verified in this review.19

What to consider. Verify account compatibility and the number of connected mailboxes. Personal and business offers should not be treated as the same package, and monthly prices should not be compared with two-year equivalents.

Score rationale

Data minimisation and transparency 4/5.: Header-based prioritisation limits body access. Optional functions have a different scope and should be checked separately.
Incoming email and documents 4/5.: Focused on organisation and reducing distractions across supported accounts. It is not assessed here as a document-extraction product.
Writing and replies 1/5.: Generative reply writing is not the core function evaluated in this entry.
Language support 2/5.: Organisation depends less on writing language; this is not a score for translation quality.
Deployment and administration 4/5.: Account-level operation can work with existing clients. Business administration options require separate review.
Value for a five-person team 4/5.: Value depends on account count, selected features and billing term. The current pricing page did not expose a verifiable amount in this review.

10. Inbox Zero18 / 30

Inbox Zero Inc., Newark, Delaware, United States · Gmail / Google Workspace, Microsoft 365, Outlook.com and Exchange

Inbox Zero sorts and labels mail, drafts replies, blocks cold email and supports bulk unsubscribe. Higher plans add integrations and other workflow features. It connects to Google and Microsoft accounts.

Processing. The privacy policy distinguishes account data from email processing. It says full message bodies are not permanently stored, while sender information, history analysis and automation metadata may be retained. Temporary summaries for active features are deleted after completion; subject lines have an active-feature exception.23

Price. Displayed annual rates: Starter USD 20/user/month equivalent; Plus USD 35; Professional USD 50. Monthly-payment terms differ.22

What to consider. Assess automated actions and account limits. SSO, SCIM and on-premise deployment are listed under Enterprise. Hosted-service pricing should not be treated as a statement about every possible use of the open-source code.

Score rationale

Data minimisation and transparency 3/5.: Detailed retention distinctions, including stored derived data. Check how those rules apply to the selected automations.
Incoming email and documents 4/5.: Automatic labels and inbox cleanup, with additional attachment filing in higher plans. Filing is not the same as structured field export.
Writing and replies 3/5.: Personalised reply drafts. Test control over style and purpose rather than assuming those controls are absent.
Language support 2/5.: The reviewed pricing page does not provide a complete language matrix; test the languages needed.
Deployment and administration 3/5.: Google and Microsoft connections; advanced enterprise controls require a separate offer.
Value for a five-person team 3/5.: Five Starter users cost USD 1,200/year at the displayed annual rate. Compare account limits and the features needed.

Frequently asked questions

What is the best AI email assistant for Gmail and Outlook?: Kerna takes first place in our editorial ranking for small teams handling customer and supplier email. It combines custom categories, reusable document fields, summaries and reply drafting in 45 languages. The ranking reflects this workflow rather than a universal benchmark.
Which tools work with my existing email account?: The listed tools use add-ons, native features or connected-account services. Check the supported provider, account type and client. A different email app does not necessarily require moving the mailbox to a new provider.
How can I check whether my email data stays in the EU?: Check application hosting, model-processing regions, retention and subprocessors separately. Kerna’s application runs in Belgium with Firestore in Poland. A contract with an EU entity or zero-retention terms alone does not prove EU-only model processing. Consult the current privacy and subprocessor documentation.
What does personal-data masking mean?: Masking removes or replaces detected personal details before model processing. Kerna uses this step across plans. It reduces exposure but should not be described as guaranteed anonymisation of every message. Retention, encryption and model-training rules are separate safeguards.
How much does an AI email assistant cost for a small team?: Compare the required features for the same users or mailboxes and billing period. Kerna Business costs EUR 69 per month for up to five users sharing 7,500,000 tokens. Existing suite AI may have no additional licence fee; new tools and upgrades should be compared on incremental cost and useful output.
Does Kerna send email on my behalf?: No. Kerna prepares drafts when requested. You review, edit and send them yourself.
Why are some email apps not included in the ranking?: The ranking focuses on assistance alongside existing Gmail and Outlook workflows. Other email clients, agent platforms and shared-workspace products may suit different needs; their exclusion is a scope choice, not a claim that they are inferior.
Where do the prices and scores come from?: Prices come from vendor materials, with billing terms stated. Scores are Kerna’s editorial judgement for the workflow described in the rubric, not independent performance measurements. Unverified current amounts are identified rather than presented as confirmed prices.

Try our top pick on your own email

Start with Kerna’s free Starter plan. Sort messages, extract document fields and prepare a reply within the included token allowance, in your existing supported inbox.

Get Kerna for Gmail Get Kerna for Outlook

See Kerna pricing

Other types of email tools

This shortlist covers native assistants, add-ons and connected services for existing Gmail or Outlook workflows. It is an editorial selection, not an exhaustive market survey. Alternative clients and broader agent platforms are discussed separately.

Superhuman. Consider separately when choosing a dedicated email interface. Changing the client does not necessarily mean migrating the mailbox provider.
Shortwave. Consider separately as an email workspace with its own interface; this ranking focuses on existing Gmail and Outlook workflows.
Spark Mail. A separate email-client choice, assessed best alongside other client replacements.
Spike. Consider separately if you want a different communication interface and team workflow.
Canary Mail. Consider separately when selecting an email client with AI features.
Missive. Consider separately for a shared team communication workspace; this shortlist focuses on assistance in existing email workflows.
Lindy. Consider separately for configurable agents and cross-application automation.
Proton Scribe. Consider alongside tools for the Proton ecosystem rather than as a Gmail or Outlook add-on.
InboxPilot. Consider separately for automated email workflows. Its exclusion is a shortlist decision, not a claim about unsupported mailbox types or Kerna’s shared-mailbox capabilities.

Sources

1. https://kerna.io/pricing read 2026-08-22
2. https://kerna.io/ read 2026-08-22
3. https://kerna.io/privacy read 2026-08-22
4. https://www.microsoft.com/en-us/microsoft-365/copilot/business read 2026-09-05
5. https://learn.microsoft.com/en-us/microsoft-365/copilot/microsoft-365-copilot-overview read 2026-09-05
6. https://www.microsoft.com/en-us/microsoft-365/copilot/enterprise read 2026-09-05
7. https://workspace.google.com/pricing read 2026-08-23
8. https://workspace.google.com/security/ai-privacy/ read 2026-09-05
9. https://www.maestrolabs.com/mailmaestro-pricing read 2026-08-22
10. https://www.maestrolabs.com/security read 2026-09-05
11. https://virtualworkforce.ai/pricing/ read 2026-09-06
12. https://www.fyxer.com/pricing read 2026-08-23
13. https://www.fyxer.com/security read 2026-09-05
14. https://www.mailbutler.io/pricing/ read 2026-08-23
15. https://www.mailbutler.io/privacy-policy-mailbutler/ read 2026-09-05
16. https://gmelius.com/pricing read 2026-09-05
17. https://gmelius.com/blog/fyxer-ai-review read 2026-08-23
18. https://gmelius.com/security read 2026-09-05
19. https://www.sanebox.com/pricing read 2026-08-23
20. https://www.sanebox.com/business read 2026-09-05
21. https://www.sanebox.com/security read 2026-09-05
22. https://getinboxzero.com/pricing read 2026-09-06
23. https://getinboxzero.com/privacy read 2026-09-06

Sources are the vendors’ pricing, product and privacy documentation. Dates refer to the cited checks, not a guarantee that every feature or commercial term remains unchanged. This ranking is published by Kerna. Send corrections to contact@kerna.io.