Bamboo Mua adapter uses SMTP relay wrong

[thefeli73]

i am unable to set up the SMTP mailer, and so far i have discovered this real issue!

Observed behavior:

1. plausible-conf.env defines SMTP_HOST_ADDR=mail.domain.com
2. plausible tries to send an email
3. bamboo looks up MX of mail.domain.com
4. MX of mail.domain.com may be something unrelated like feedback-smtp.eu-north-1.amazonses.com., for dmarc monitoring
5. bamboo looks up A record of feedback-smtp.eu-north-1.amazonses.com.
6. bamboo tries to establish SMTP connection to non-SMTP server.
7. {:error, %Mua.TransportError{reason: :timeout}}

Expected behavior:

1. plausible-conf.env defines SMTP_HOST_ADDR=mail.domain.com
2. plausible tries to send an email
3. bamboo looks up A of mail.domain.com
4. bamboo tries to establish SMTP connection to SMTP server which was specified.
5. profit.

[ruslandoga]

👋 @thefeli73

This indeed seems like a wrong way to use SMTP relay. I've created an issue ruslandoga/bamboo_mua#47 and will fix it tomorrow. Thank you for taking time to report it!

[ruslandoga]

PR: #4350

[ChristopheKar]

I'm not sure if the introduction of the Mua adapter affected other things, but my problem also extends to the Bamboo.SMTPAdapter in this new v2.1. I had a previous setup with v2.0 that was working well, but updating to the new version breaks email using both Bamboo.SMTPAdapter and Bamboo.Mua.

If I keep the same docker-compose.yml file but simply revert the Docker image from ghcr.io/plausible/community-edition:v2.1 to plausible/analytics:v2.0, email works again.

[ruslandoga]

👋 @ChristopheKar

Erlang version changed between v2.0 and v2.1 and the new Erlang version introduced more strict TLS defaults and peer verifications. This broke Bamboo.SMTPAdapter since it didn't allow peer verification configuration and Erlang requires it and is the reason for Bamboo.Mua introduction. If you share the problems you are having with Bamboo.Mua it's very likely we will find a workaround. Based on previous discussions here and in the issues it usually involves some extra TLS configuration and is relatively easy to do.

[ruslandoga]

To save time, you can also try searching the discussions for "mua" or "smtp" to find common problems and their workarounds.

[ChristopheKar]

My bad, I somehow missed the relevant discussion #4149. One of your suggestions in that conversation worked well for me, thank you for your work and prompt responses!

[thefeli73]

i finally fixed my issue. i had fatfingered an ip idress in the firewall for port 587. since i only tried port 465 for the longest time, which still doesnt work, i never thought to check if plausible can reach my mailserver on port 587, since 465 was reachable.