Outgoing Mails issue via port 25

[perag]

My ISP seems to be blocking Port 25 which is needed for outgoing mails due to security concern. How can i assign another port. Plz could someone help with necessary steps for doing the change.

 

[Zella]

By default qmail already uses 2 ports :
Standard SMTP on port 25
and
SMTPS (SMTP/SSL) on port 465

Then you can try the port 465.

Or

you can also add a new port for SMTP.

Modify the file /etc/services
Add a line like this :

smtp your-port/tcp
smtp your-port/udp

ex:
smtp 26/tcp
smtp 26/udp

BUT DON'T REMOVE the lines
smtp 25/tcp
smtp 25/udp

Save and close the file /etc/services
Then restart the xinetd service with
service xinetd restart
That's all.