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When I try to telnet to the mail server on port 25 I see the following:What happens when you try this from a working machine. Do any firewall rules either on the machine or somewhere else block it.
Connected to hostname.domain
Escape character is '^]'.
Connection to hostname.domain closed by foreign host.
Ok, so you may have "netservices limited" set on this one sever. So, send an email message to a user on the same server. Then send a message to a user on a different server on your side of the firewall. Or just use telnet again. If it goes through then your being blocked somewhere on your side.
If I send an email to a user on the same server, it seems that is sent through. If I try to send an email to a user on a different server on the same subnet, it seems to hang when it gets to the point below:
MAIL FROM: user1@servername
RCPT TO: user2@servername
Enter mail, end with "." on a line by itself
Also, I cannot telnet to the smtp server on port 25
# telnet <smtpserver> 25
Connected to <smtpserver.domain>
Escape character is '^]'.
Connection to <smtpserver.domain> closed by foreign host.
I'm not sure what "netservices limited" means?
Hope this makes sense.
This was a network issue. A network port going to a switch had been unplugged due to fault on the switch. So, traffic was only passing through one network port and switch instead of the two switches. Now the fault on switch has been resolved and port was plugged back into the switch, it seems email is working ok now. Traffic is going through ok. Will monitor it over the next few days.
Hopefully, you checked that it's not the same network switch port issue again?
Perhaps your switch admin is setting up VLANs or access restrictions there?
Are other network communications to a system on the same subnet as the mail server working?
How about to other network ports i.e telnet, ssh, rlogin, etc.?
/EXACT/ same symptoms as last time with respect to connecting directly to the mail server on port 25?
no real ideas, just brainstorming.
No there haven't been any vlan restrictions configured.
Other servers on the same subnet have mail working.
Other ports on the problematic server are ok. i.e ssh is working fine.
The exact same problem.
What happens now is, the server can telnet to the mail server on port 25 sometimes, and other times I seem to get a connection closed by foreign host.
Is the mail server a Solaris machine? If so, or even if it is not, there should be a syslog
or /var/adm/messages to check and see if there is anything interesting being recorded.
I assume those other servers on the same subnet are connecting to the same
problematic outbound mail server?
It may be time to break out "snoop", Wireshark or your favorite network trace tool.
Ideally, you will be able to snoop/trace both sides on port 25 and reproduce the failure.
Odds are good no one here can help you.
You seem to be having some sort of network issue. You can try another switch port, swap cables, whatever. But until you have a guaranteed nailed up connection we can't help. Take to your networking folks and have them assist. It might even be a flaky network port on the Sun box but you need to troubleshoot the intermittent network disconnects.