[Note: I asked ask.discourse.org to write this post based on a troubleshooting conversation.]
I’ve been investigating the “mail-receiver deprecation warning on ‘email’ parameter” issue on my self-hosted site, and I wanted to share what I’ve confirmed in case it helps get a fix shipped.
Symptom
Every incoming email via mail-receiver produces this in the logs:
DEPRECATION NOTICE: warning: the email parameter is deprecated. all POST requests to this route should be sent with a base64 strict encoded email_encoded parameter instead. email has been received and is queued for processing (removal in Discourse 3.3.0)
At /var/www/discourse/vendor/bundle/ruby/3.4.0/gems/actionpack-8.0.5.1/lib/action_controller/metal/basic_implicit_render.rb:8:in `ActionController::BasicImplicitRender#send_action`
What I’ve verified on my server
base_image: discourse/mail-receiver:releasein/var/discourse/containers/mail-receiver.yml— so I’m running on thereleaseline, not a pinned old version.docker psshowslocal_discourse/mail-receiverrunning alongside the standard app container.docker image inspect local_discourse/mail-receiver --format '{{.Created}}'→2026-08-08T08:41:54Z— freshly rebuilt with./launcher rebuild mail-receiverjust days ago.- The deprecation notice persists after a fresh rebuild on
release.
Conclusion
The warning is coming from the current latest release of mail-receiver itself, which still sends the raw email under the deprecated email parameter rather than the base64 strict-encoded email_encoded parameter the endpoint now expects. As far as I can tell, nothing in the running release image resolves this yet.
It’s only a deprecation notice (not an error) and email is still queued and processed normally, so it’s not breaking my site — but I’d love to see the mail-receiver code updated so this warning goes away. The offending line is in discourse_mail_receiver.rb, which posts the email param instead of email_encoded.
Is there any timeline for shipping this fix in the mail-receiver release image?