メールシステムの構成について質問があります

[hawm]

It could be the port 465 issue.

Discourse with other websites, SMTP issue: End of file reached

Before I saw this I was going to recommend this change. Port 465 is SMTP-over-SSL, which is deprecated Port 587 is the MSA port (mail submission agent) on which STARTTLS (upgrade from a plaintext to a TLS connection) is typically supported When you had 465 in the configuration, Discourse was trying to talk plaintext to an SSL port.