Kerna vs Mailbutler Smart Assistant
Kerna
kerna.io
Mailbutler Smart Assistant
mailbutler.ioSide by side
| Figure | Kerna | Mailbutler Smart Assistant |
|---|---|---|
| Price from | €12/mo | $7/mo |
| Free plan | Yes | Yes |
| Free trial | — | Yes |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | — | Yes |
| iOS | — | Yes |
| Android | — | Yes |
| Plans published | 5 | 10 |
| Spec score · AI Email Assistants | 8.3 (#11) | 9.2 (#3) |
| Headquarters | Katowice, Poland | Berlin, Germany |
| Integrations | Kerna integrates with Gmail, Outlook, Calendar, Contacts and Sheets, and the pricing page lists shared mailboxes for Outlook. | Business plans sync tracking events with HubSpot and Salesforce and support Google Analytics 4 UTM data. |
| Product | Kerna is an AI email assistant that works inside Gmail and Outlook. | Mailbutler presents Smart Assistant as an AI email assistant for Apple Mail, Gmail, and Outlook. |
| Security | The trust page reports TLS 1.2 or higher in transit and AES-256 encryption at rest in Firestore. | Mailbutler says it is ISO/IEC 27001 certified and GDPR compliant, and that backend data is encrypted. |
Plans
Kerna
- StarterFree
- Standard€12 a month
- Pro€22 a month
- Business€69 a month
- Enterprise€499 a month
Mailbutler Smart Assistant
- StarterFree
- Professional$9 a month
- Smart$14 a month
- Business$32 a month
- Professional (yearly billing)$7 a month
- Professional (monthly billing)$9 a month
- Smart (yearly billing)$11 a month
- Smart (monthly billing)$14 a month
- Business (yearly billing)$24 a month
- Business (monthly billing)$32 a month
In their own words
Kerna
Kerna is an AI email assistant for Gmail and Outlook on macOS, Windows, and the web. At a user’s request, it sorts open messages into categories such as Urgent, Respond, Invoice, Waiting, and Notification; users can also set custom categories and industry taxonomies. It drafts replies based on the full thread, with controls for intent and tone, and makes structured thread summaries for conversations of up to 50 messages. It can summarize attachments, extract selected fields into exportable tables, and translate inbound messages and outbound replies in 45 languages. Integrations include Calendar, Contacts, and Sheets as well as Gmail and Outlook. Kerna says it acts only when a user initiates a request, processes content in memory, discards it afterward, and redacts personal data before it reaches the inference provider. Its trust information reports TLS 1.2 or higher in transit and AES-256 encryption at rest. Kerna has a free plan; paid plans start at €12/mo. Outlook requires a Microsoft-hosted mailbox; POP or IMAP and on-premises Exchange are unsupported.
Mailbutler Smart Assistant
Mailbutler Smart Assistant adds AI writing and email-management tools to Apple Mail, Microsoft Outlook, and Gmail. It drafts messages from keywords or prepares replies using details a user supplies, with controls for format, length, style, tone, and language. It can summarize selected emails, identify to-dos for Mailbutler Tasks, and suggest spelling and grammar improvements to drafts. Mailbutler says the assistant uses OpenAI GPT-4o. Smart Assistant is included in a 14-day trial, then requires a Smart or Business subscription. The separate free Starter plan includes a visible Mailbutler watermark on sent emails. Mailbutler says email subjects and bodies are processed by Microsoft Azure OpenAI Service in the EU, with personal data redacted before submission to the underlying model. It also says backend data is encrypted and that it is ISO/IEC 27001 certified and GDPR compliant. Apple Mail support is listed for macOS Tahoe, Sequoia, Sonoma, and Ventura; mobile apps require iOS 15 or later or Android 7 or later.