I have tried 10 different emails hosted at Google, Yahoo!, GoDaddy, and some that are privately hosted, and each time I get the following errors. I have blocked sensitive information, but you will be able to see the errors.
Feb 16 17:06:50 xxxxx sendmail[31824]: o1GM6ovJ031824: to=jxxxxxd@att.net, ctladdr=www-data (33/33), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30054, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (o1GM6oJo031825 Message accepted for delivery)
Feb 16 16:54:19 xxxxx sendmail[31625]: o1GLsJPP031625: to=jeremy@hxxxxxc.com, ctladdr=www-data (33/33), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30097, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (o1GLsJah031626 Message accepted for delivery)
Feb 17 09:05:52 xxxxx sm-mta[10620]: o1H6Z3jM005734: to=<jeremy@hxxxxxc.com>, ctladdr=<www-data@xxxxx.corenetworks.net> (33/33), delay=07:30:49, xdelay=01:15:36, mailer=esmtp, pri=571331, relay=aspmx3.googlemail.com. [209.85.222.4], dsn=4.0.0, stat=Deferred: Connection timed out with aspmx3.googlemail.com.
Feb 17 10:35:23 xxxxx sm-mta[12828]: o1HEZwn8011833: to=<jxxxxxd@att.net>, ctladdr=<www-data@xxxxx.corenetworks.net> (33/33), delay=00:59:25, xdelay=00:12:36, mailer=esmtp, pri=300353, relay=aln-mailrelay.att.net. [12.102.252.75], dsn=4.0.0, stat=Deferred: Connection timed out with aln-mailrelay.att.net.
If you take a look, they all send, but then (HOURS later) I get an error "stat=Deferred: Connection timed out with {server}". I'm at my wits end, because I use this same setup on each of my servers, and they all work.
Best Answer
if you cant use port 25 you can normally use port 587 as this is the SMTP delivery port that was designed to be used between servers.
Test that out if your ISP block port 25.
DNS looks to be working also as it returns the IP addresses of the remote servers. Yes, test port 587 and send out on that port instead.
edit: tested it works for me on 25.
~$ telnet aspmx3.googlemail.com 25 Trying 72.14.213.27... Connected to aspmx3.googlemail.com. Escape character is '^]'. 220 mx.google.com ESMTP q20si8879349rvl.138