I am trying to setup a email server on Google clou for which I have used iRedMail. I have followed this link to setup. There was no error in logs while sending email to this email server but when I try to send from the UI to my email ID it is giving me following error in logs. ( /var/log/mail.log ).
Dec 8 10:19:36 comm postfix/smtp[4142]: connect to mail.tinydef.com[157.230.67.25]:25: Connection timed out
Dec 8 10:19:36 comm postfix/smtp[4142]: 4J8CnP4ND5z3ygl: to=<[email protected]>, relay=none, delay=31, delays=0.02/0.03/31/0, dsn=4.4.1, status=deferred (connect to mail.tinydef.com[157.230.67.25]:25: Connection timed out)
I am aware that port 25 is blocked on GCP. Just trying to figure a way out from this situation. Is there any configuration that can be tweaked to change port 25 to some other port ?
You cannot send mail to external IP addresses on port 25 from instances in Google Cloud. There is no appeal process to change this policy.
Sending email from an instance
To function as a mail server requires communication between servers on port 25. Mail relays can use any port the mail server supports except for port 25.
iRedMail can function as a traditional mail server, which requires port 25, and as a mail relay to forward mail to a mail server.
Setup relayhost
Your solution is to configure iRedMail as a relay host forwarding mail on port 465 or 587 to a mail service such as Gmail, Office 365, SendGrid, etc. The email service will deliver your email.