I am able to sent mail using postfix with dovecot via Thunderbird app but when I am trying to send a mail using roundcube web UI then i am getting SMTP error(): connection to server failed
So what need to be check and any modification required?
If Thunderbird works but Roundcube doesn't, it's likely an SMTP config issue.
I'm working on the same issue, I use a CRM and send and receive and RoundCube I receive but like you get an smtp connection error
I found one error in the config, I miss spelled the database so I wasn't connecting even to the database but I still get an smtp error.
I'm also using virtual mail domains
I found the error I made, I had the wrong name in dovecot config and roundcube config.