In /var/log/mail.log I see runs of time-out errors in quick succession, like this

Dec 13 15:50:31 myserver postfix/smtp[2911]: connect to alt2.gmail-smtp-in.l.google.com[74.125.138.26]:25: Operation timed out
Dec 13 15:50:31 myserver postfix/smtp[2910]: connect to alt2.gmail-smtp-in.l.google.com[74.125.138.27]:25: Operation timed out
Dec 13 15:50:31 myserver postfix/smtp[2913]: connect to alt2.gmail-smtp-in.l.google.com[74.125.138.26]:25: Operation timed out
Dec 13 15:50:31 myserver postfix/smtp[2916]: connect to alt2.gmail-smtp-in.l.google.com[74.125.138.27]:25: Operation timed out
Dec 13 15:50:31 myserver postfix/smtp[2914]: connect to alt2.gmail-smtp-in.l.google.com[74.125.138.26]:25: Operation timed out

Telnet also times out (though it takes ~75 seconds):

% telnet 74.125.138.26 25
Trying 74.125.138.26...
telnet: connect to address 74.125.138.26: Operation timed out
telnet: Unable to connect to remote host

So it looks to me like my port 25 is blocked.

I know that my ISP does not block my port 25 (I've connected through it routinely, as recently as yesterday), so I figure that the blocking is happening locally.

How can I unblock this port?

(If possible, I'd much prefer a command-line solution, rather than a GUI-based one.)

  • You should use traceroute alt2.gmail-smtp-in.l.google.com to check if it is your problem or it's outside. – jherran Dec 13 '14 at 21:32
  • Those logs seem to indicate that it is not your port 25 that is blocked, but theirs, or some entity along the network path is filtering the traffic. or it could just be that the remote service is down. timeout messages don't really tell you anything except that it didn't work, with no detail as to why. – Frank Thomas Dec 13 '14 at 22:00

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