mello vs Fastmail
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Fastmail and mello have a lot in common. Both are independent mail services, and both work with any mail app over open standards. Fastmail has run since 1999, from Melbourne; mello is newer, written from scratch and run from Switzerland. Here is where they differ.
At a glance
What the table says about Fastmail comes from Fastmail’s own pages, as of October 2026.
| Fastmail | mello | |
|---|---|---|
| Other mail apps | IMAP, POP, SMTP, CalDAV and CardDAV (not on the Basic plan) | IMAP, SMTP, CalDAV and CardDAV |
| Encryption | Stored on encrypted disks; not end-to-end encrypted in its own apps | TLS on every connection, MTA-STS and DANE between servers; not end-to-end encrypted |
| Your own domain | On most plans | Not yet |
| Aliases | Masked Email, also from 1Password and Bitwarden | Private addresses, built in |
| AI | None built in; an MCP server for AI tools you connect | On by default, and you can switch it off; an MCP server for Claude and ChatGPT |
| Plans | No free plan; a free trial of up to 30 days | A free plan and paid plans; invite only for now |
When Fastmail is the better choice
- You want your own domain. Most Fastmail plans include custom domains. In mello, you can’t add your own domain yourself yet.
- You want two-step verification. Fastmail supports it. mello doesn’t offer it yet, so choose a long, unique password.
- You want to pick where your data lives. Fastmail lets you choose the EU or the USA for your data.
- You want encryption at rest, or PGP. Fastmail stores your data on encrypted disks, and points you to PGP or S/MIME in third-party apps for end-to-end encryption.
- You want a long track record, and an account today. Fastmail has been running since 1999 and is open to everyone. mello is new, and invite only for now.
- You want no AI at all. Fastmail has no built-in AI features. mello’s assistant is on by default, and you can switch it off in Settings → AI.
Where mello is different
- An assistant that remembers. It is on from the start, and it can suggest a follow-up when a message you sent gets no reply in 3 days, bring back mail waiting on your answer after 7 days with a reply drafted, suggest to-dos from new mail, write a draft when you type
/aiand what to say, and translate a message. Message text goes to the AI provider (Anthropic or OpenAI) for the features that are on; turning them off under Settings → AI stops it. - Tasks, next to mail. To-dos live beside your mail and calendar, sync to your phone over CalDAV, and can come from a message.
- Mail that waits. Snooze, send later, undo send and follow-up reminders run on the server, so they work in any mail app, even with all of them closed.
- Booking links. Share a page where people pick a free slot in your calendar. See the booking page.
- Keyboard first, and in the terminal. A command palette and a shortcut for everything in the webmail, and a command-line client for scripts.
- Spam that explains itself. Every message in Junk says, in plain words, why it is there.
Connecting your own AI
Both services have an MCP server, so you can connect an assistant such as Claude or ChatGPT to your mailbox. Fastmail’s is at https://api.fastmail.com/mcp, and lets you grant read, write and send access separately. mello’s is at https://mcp.mello.mx/mcp: an assistant can find, read and organize mail, prepare drafts, and keep your calendar, tasks and contacts, and it can only send if you tick that box when you connect it. See connecting ChatGPT and Claude.
How to switch
mello has no importer, but both services speak IMAP, so moving is simple:
- Forward your new mail from Fastmail to your mello address.
- Add both accounts to Thunderbird or Apple Mail, and drag your folders from Fastmail to mello. How to move from Gmail shows the same steps in detail.
- Export your contacts from Fastmail as a .vcf file, and import it in mello under Contacts → Import.
- Export your calendars as .ics files, and import them through Apple Calendar or Thunderbird once your mello account is set up there.
mello is invite only for now: request an invite.