Question Cannot connect to SMTP server on localhost using tls (or ssl)

[Kroptokin]

Server operating system version

AlmaLinux 9.6 (Sage Margay)

Plesk version and microupdate number

Plesk Obsidian 18.0.70 Update #1 Web Host Edition

On local host I can connect to the SMTP server using basic authentication on port 25 but I cannot connect using tls or ssl. (I am trying to connect from code).

I have tried ports 465 and 587. (I cannot telnet to 587 but I can to 465).

I just get "Connection refused" from my client library.

I don't really know what I should be looking for. There is no SSL certificate for mail on the domain - but I don't think that matters. The server mail certificate is the default. The server web certificate is one for a domain - but that is for web access, not mail.

I don't really know what I should be looking at. AI is suggesting editing a posffix config file, but I would rather avoid that.

 

[Kaspar]

Is there any particular reason you're using localhost? Because instead you could also try to use the server host name to make an SMTP connection. Which by default is secured for SMTP connections.

 

[Kroptokin]

Thanks @Kaspar - it does try to connect when I use the Plesk server hostname. But now, a message about 'incorrect certificate'. I tried on ports 468 and 587, So; it looks like progress but not there yet. Will keep trying, thanks for your input.

 

[Kaspar]

Actually, for what it's worth, connecting to localhost via port 25 is just as secure (if you are the administrator of the sever) as using a secured SMTP connection trough a domain/host name. It's an local connection, so there isn't much point in using SSL/TLS.

 

[Kroptokin]

Yes. I have understood that. Thanks!