Smtp

I just finished moving my Gmail “Send mail as” setup to Cloudflare Email Service’s native SMTP submission. I can send email from my mindflakes.com address.

I built the SMTP relay described here with the assistance of Codex. I supplied the idea and directed the work; Codex did the technical investigation and implementation. Codex also drafted this post.

Update, October 12, 2026: Google is removing Gmail’s “Send as” support for third-party addresses in January 2027. Google’s announcement says existing setups continue during the transition, but new configurations may be restricted. Gmail-to-Gmail aliases and Google Workspace “Send as” are exempt. Incoming forwarding is unaffected. The sending setup described here now has an end date. Darn, I was looking forward to this for years. The rest of this post describes what worked in June.

Back in April, I had built a small Rust SMTP-to-Cloudflare REST API relay. Today I noticed Cloudflare had shipped native SMTP submission.

Part of the appeal here is minimizing vendors. Cloudflare already hosts the domain, handles incoming mail through Email Routing, and now can handle outgoing mail through Email Service too. For a personal domain, that can be cheap or free, and it is a nice alternative to paying for Google Workspace when a personal Gmail account is otherwise fine.