Kerna

Kerna is an AI email assistant for Gmail and Outlook, built for professionals who want deliberate help with demanding inboxes. It is a strong fit for individuals and teams that need triage, drafting, summaries, attachment extraction and translation in one workflow, provided an Outlook account uses a Microsoft-hosted mailbox.

Overview

Kerna brings a broad set of email tools into the mail clients many workplaces already use. Assistance starts only when the user requests an action, so it does not silently scan the inbox in the background. That is a meaningful control for privacy-conscious users, but it also means Kerna is not an unattended inbox-automation system.

Email content is processed in memory and discarded after the request, with personal data redacted before content reaches the inference provider. Kerna reports TLS 1.2 or higher in transit and AES-256 encryption at rest in Firestore. Its Gmail add-on has CASA Tier 2 validation. The Microsoft Publisher Attestation is described as a self-assessment, not independent verification or Microsoft 365 Certification.

Key features

Triage and drafting

On request, Kerna sorts open messages into Urgent, Respond, Invoice, Waiting and Notification. Custom categories and industry taxonomies make the feature more useful for specialist workflows than a fixed five-label system. Since sorting is initiated by the user, it suits people who want a controlled review step rather than automatic background classification.

Reply drafts use the complete thread history, and users can set an intent and tone. Tone controls and custom instructions provide practical ways to steer wording while keeping the conversation as context. This is especially useful when a response needs to match a role or communication style, though the workflow still depends on the user launching the action.

Summaries, attachments and translation

Kerna creates structured summaries for threads of up to 50 messages, giving long conversations a defined working limit. It can summarize attachments and extract chosen fields into tables that can be exported to files, a valuable option for invoices and other repetitive document-based email tasks.

Translation covers inbound messages and outbound replies in 45 languages. Kerna also integrates with Calendar, Contacts and Sheets, alongside Gmail and Outlook, while shared Outlook mailboxes are included in the pricing feature set.

Pricing

Kerna uses a freemium model. Starter costs nothing and includes 30,000 trial-volume tokens, GPT-5.6, all features and a single-user license. It is suitable for evaluating the full toolkit, but the token allowance is finite.

Standard costs €12 a month, billed monthly, with 500,000 standard-usage tokens, GPT-5.6, all features and one user. Pro costs €22 a month, billed monthly, and raises the allowance to 1,000,000 power-usage tokens for one user. These plans suit individuals whose main constraint is usage volume rather than collaboration.

Business costs €69 a month, billed monthly, and provides a 7,500,000-token shared pool, five team seats, shared prompts and billing, with no wasted credits. Enterprise costs €499 a month, billed monthly, and expands that shared pool to 50,000,000 tokens across 25 seats, adding processing-log and CSV export capabilities plus priority contact. Those tiers are aimed at coordinated teams and larger organizations; they cost more because capacity and administration are shared across users.

Platforms

Kerna is available on macOS, Windows and the web. It supports both Gmail and Outlook. Outlook users need a Microsoft-hosted mailbox; POP or IMAP connections and on-premises Exchange mailboxes are unsupported.

Who it's for

Kerna is a good choice for professionals handling substantial email volume, especially when attachments, multilingual correspondence or structured extraction are part of the job. Business and Enterprise plans make sense for teams that need pooled tokens, shared prompts or multiple seats. Users wanting automatic background processing, unsupported Outlook mailbox types or a simple unlimited drafting tool should look elsewhere.

Pros and cons

• Pros: One assistant covers triage, thread-aware drafting, summaries, attachment tables and 45-language translation.
• Pros: User-triggered processing, in-memory handling and personal-data redaction provide clear control over when email content is processed.
• Pros: Shared token pools and seats support team use without separate individual allowances.
• Cons: Outlook support excludes POP, IMAP and on-premises Exchange mailboxes.
• Cons: Every paid tier is token-limited, so heavy users must monitor consumption.
• Cons: Processing is not automatic; each action must be initiated by the user.

Alternatives

For a broader shortlist, see AI Email Writing Tools and AI Email Assistants.

WPS AI Email Writer is the better pick if you want free, unlimited email writing across a wider range of platforms with no signup and no ads.

WriteMail.ai suits users who prefer clearly metered monthly email quotas, starting at 50 AI emails for $6.95 a month.

AI Perfect Assistant is worth choosing when Microsoft 365, Chrome and Telegram integrations matter more than Kerna's mailbox-centered toolkit.

ForthWrite is an alternative for users wanting a free tier with 10 drafts per week for Gmail and Outlook on the web.

Ellie fits users who need a free allowance of 10 draft replies per day and one connected account.

GPT for Gmail is an alternative focused on Gmail.

Jetwriter AI is an option for extension and web users who want a small free monthly response allowance.

Lavender is an alternative for users seeking email analysis and personalization through an extension or web app.

Verdict

Choose Kerna if you want a single Gmail or Outlook assistant that combines controlled triage, context-aware drafting, document extraction and multilingual support, with team plans when usage is shared. Look elsewhere if you need background inbox automation, an unsupported Outlook mailbox, or pricing without token ceilings.