What ports to block emails out?

stefeman

as title says, suppose I want to cripple all outgoing email spam/traffic from my servers via port blocking only, is it enough to block SMTP port 25?

solaire

Port 587. Port 2525 may be supported on some systems too.

Janevski

outgoing mail:

smtp - tcp 25

smtps - tcp 465

PS: Also block 26 and 587.

eol

To be absolutely sure and for additional security block all ports from 0 to 65535.

jamespeach

@eol said:
To be absolutely sure and for additional security block all ports from 0 to 65535.

Dearest eol,

This would block every port on the machine ensuing nothing would have access to the internet. Is this your intention?

With Warm Regards,
James B Peach

eol

Yes, and vice versa.

sleddog

Don't block specific ports.

Instead, block everything. Then allow specific ports for the services your server is running.

eol

Exactly.