SendAs Relay by Adam Hale

Google is removing "Send mail as" for non-Gmail addresses. From January 2027, Gmail on the web won't send from your Yahoo, iCloud, Fastmail, GMX, ISP or own-domain address (Gmail Help article 17101213). SendAs Relay brings that back.

Beta: please read. SendAs Relay has been tested end to end against a copy of Gmail's compose window and against real SMTP servers, but not yet on live Gmail. If Gmail's page doesn't look the way the extension expects, it refuses to send rather than send something incomplete, and offers "Send with Gmail instead". Please report anything that doesn't work to adam.hale@atomicmail.ai.

What it does
- Adds a From menu to every Gmail compose window: new messages, replies and forwards.
- When you pick one of your other addresses, Send and Ctrl+Enter go through that address's own SMTP server instead of Gmail.
- Replies to mail sent to your other address use that address automatically and stay in the same thread (In-Reply-To and References headers).
- Saves a copy in Gmail's Sent Mail (IMAP, with a Gmail app password), or Bcc's it to your Gmail, or keeps no copy. Your choice.
- Attachments, inline images, Cc and Bcc work. The Bcc list is never shown to recipients.
- Pick your Gmail address in the menu and Gmail sends as usual. Nothing changes.

How it works
Browsers can't talk to mail servers directly, so each message passes through a small relay that connects to your provider's SMTP server, sends the message and forgets it. The relay is a Cloudflare Worker: it stores nothing, keeps no logs, and its code is open source (MIT). During the beta there is no hosted relay: you deploy your own copy on a free Cloudflare account (step-by-step guide: https://sendas-relay.adamhaleworks.workers.dev/self-host/) and paste its URL into the setup screen.

Privacy and security
- Your SMTP passwords and settings are stored only in your browser. Add a passphrase to encrypt them (AES-256-GCM, PBKDF2 with 600,000 rounds). You type it in an extension window, never on the Gmail page.
- When you send, the message and that address's SMTP login go to the relay over HTTPS for that one connection. Nothing is kept.
- The extension reads a Gmail compose window only when you click Send with another address selected. For replies it fetches the original message's headers from your own Gmail session to keep the thread together.
- No analytics, no tracking, no ads. No account to create.

What you need
An address whose provider allows SMTP sign-in: Yahoo, AOL, AT&T, iCloud, GMX, Web.de, Fastmail, Zoho, Purelymail, Migadu, Forward Email, ImprovMX, Brevo, SMTP2GO, Mailjet, Resend, Mailgun, Comcast/Xfinity, or any other SMTP server on port 465, 587 or 2525. Most providers want an app password; setup links to each provider's instructions, and "Test connection" checks it before you save.

Not supported (yet)
- Outlook.com / Hotmail: Microsoft has accepted only Microsoft sign-in (OAuth) for SMTP since 16 September 2024. Planned.
- Proton Mail: SMTP only works through Proton Bridge on your own computer.
- Scheduled send, undo send and confidential mode for other addresses (Gmail's own send is still there for your Gmail address).
- Gmail mobile apps (this is a desktop browser extension).

Free and Pro
Free: one address, all features. Pro: unlimited addresses, with an offline licence key; nothing is checked online. (Pro isn't on sale yet.)

Not affiliated with or endorsed by Google. Gmail is a trademark of Google LLC.