When trying to send mail from the Production server, we are getting:

[pnh29cbes]

No such file or directory
Dec  6 12:56:35 gdcm1 sendmail[13318]: pB6HuYO13318: Saved message in /var/tmp/dead.letter
Dec  6 12:56:35 gdcm1 sendmail[13318]: pB6HuWO13308: pB6HuYQ13318: postmaster notify: ":include:/etc/main/postmasters.list"... Cannot open /etc/main/postmasters.list: No such file or directory
Dec  6 12:56:35 gdcm1 sendmail[13316]: pB6HuYQ13316: Saved message in /var/tmp/dead.letter
Dec  6 12:56:35 gdcm1 sendmail[13318]: pB6HuYQ13318: pB6HuYR13318: return to sender: ":include:/etc/main/postmasters.list"... Cannot open /etc/main/postmasters.list: No such file or directory
Dec  6 12:56:36 gdcm1 sendmail[13318]: pB6HuYQ13318: Saved message in /var/tmp/dead.letter

EXPN/VRFY/ETRN during connection to MTA
Dec  6 13:03:25 gdcm1 sendmail[16332]: NOQUEUE: ip address [172.21.42.68] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Dec  6 13:03:25 gdcm1 sendmail[16338]: NOQUEUE: ip address [172.21.42.68] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Dec  6 13:03:25 gdcm1 sendmail[16333]: NOQUEUE: ip address [172.21.42.68] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Dec  6 13:03:25 gdcm1 sendmail[16337]: NOQUEUE: ip address [172.21.42.68] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA
Dec  6 13:03:25 gdcm1 sendmail[16328]: NOQUEUE: ip address [172.21.42.68] did not issue MAIL/EXPN/VRFY/ETRN during connection to MTA

Your responses appreciated. Points will be assigned

Rgds

Pnh29cbes

[Patrick Wallek]

The first thing I see is that the system is apparently trying to include information from the /etc/main/postmasters.list file and that file does not exist.

The second error indicates that you are connecting to mail server, but the connection is being dropped before any work can be done.  Verify that your production server is allowed to connect to your SMTP mail server.