Good info to keep in mind.
So many questions can be answered by running through a full telnet message send. I use it pretty often. I often have to cheat for the format and order but it's a very useful troubleshooting aid. It's worth it for anyone beginning in the "Art" of email servers to keep that tool handy in their toolbox. Do a google for "telnet SMTP" if you don't know what we're talking about. It's also one the veterans need to remember is there... > To those that may run into the issue: > The Watchguard firewall (hardware firewall) features a SMTP/POP proxy > service that can cause you issues. You will receive mail normally but > when your clients try and send email on port 25 (from outside the > firewall/DMZ) they will receive errors in Outlook saying: > > The message could not be sent because one of the recipients was rejected > by the server. The rejected e-mail address was '[email protected]'. > Subject 'test email ', Account: 'mail.test.com', Server: > 'mail.test.com', Protocol: SMTP, Server Response: '553 Requested action > not taken: mailbox name not allowed or chunk too large', Port: 25, > Secure(SSL): No, Server Error: 553, Error Number: 0x800CCC79 > > And you will see this in the QMT SMTP logs: > > @4000000049f7e4891f360f14 tcpserver: pid 20516 from 263.299.178.229 > @4000000049f7e4891f382a24 tcpserver: ok 20516 db3:10.10.0.12:25 > :263.299.178.229::3482 > @4000000049f7e48a194cebcc CHKUSER accepted sender: from > <[email protected]::> remote <etg91:unknown:263.299.178.229> rcpt <> : > sender accepted > @4000000049f7e48a3142fc1c CHKUSER rejected relaying: from > <[email protected]::> *_remote <etg91:unknown:263.299.178.229> rcpt > <[email protected]> : client not allowed to relay > _...@4000000049f7e48c105caad4 tcpserver: end 20516 status 0 > @4000000049f7e48c105cc244 tcpserver: status: 0/100 > > > > This will cause outgoing mail to fail when authenticating on port 25, > but will function correctly on port 587. > This caused some hair to plug up my keyboard from pulling it for a > couple hours - the client never made me aware there was a SMTP proxy in > place. I found out when I attempted to telnet into their IP address and > did not receive the SMTP greeting that I was expecting. > > Hopefully this will help someone else in the future. > >
