Port 25 blocked, Im not using port 25

I am not using port 25 but all of my emails are bouncing back with message :25 connection refused.  I am using Imap ports exclusively.  Why are emails coming back to me after I blocked 25 on CSF?

Can you elaborate a little bit?

What port *are* you using for outbound SMTP, then, if you've blocked port 25?

I am using port 587 in thunderbird.  If I block port 25 in csf firewall my mail comes back.

bump

I am facing exactly the same issue, I receive but I can't send e-mail, take error port 25 even if I use thunderbird and send via port 587.
Did you find any solution?

I could not understand too.
You're having a problem with a mail received in your server, or you have problem with your mail reader trying to send mail through your server..??

Regards,
Netino

Reading carefully the post, looks like my issue isn't the exactly the same.

I can receive e-mail but I can't send, I use thunderbird and port 587 to send e-mails but when I check mail logs I see this:
"...delay=none, delay=164006, delays=164006/0.01/0/0, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to hotmail-com.olc.protection.outlook.com[104.47.1.33]:25: Connection timed out)"

It looks like postfix uses only port 25. I want to mention that port 25 is blocked to my VM.

Reading carefully the post, looks like my issue isn't the exactly the same.

I can receive e-mail but I can't send, I use thunderbird and port 587 to send e-mails but when I check mail logs I see this:
"...delay=none, delay=164006, delays=164006/0.01/0/0, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to hotmail-com.olc.protection.outlook.com[104.47.1.33]:25: Connection timed out)"

It looks like postfix uses only port 25. I want to mention that port 25 is blocked to my VM.

then you need to use external mail server which have port 25 open or sendgrid or similar Email Delivery Services.

I have configured Postfix to send mail using Gmail, and it works great. However, this is a temporary solution.