Testing sendmail

Follow these steps to run sendmail in test mode:

1.  Type /usr/lib/sendmail -bt and then press Return. Information is displayed.

2.  At the last prompt (>), type 0 e-mail-address and then press Return. See Chapter 4 for a complete description of the diagnostic information.

Verifying Connections to Other Systems

To verify connections to other systems, you can use the mconnect program to open connections to other sendmail systems over the network. The mconnect program runs interactively. You can issue various diagnostic commands. See the mconnect(1) manual page for a complete description.

If you cannot use mconnect to connect to an SMTP port, check these conditions:

•  Is the system load too high?

•  Is the sendmail daemon running?

•  Does the system have the appropriate /etc/mail/sendmail.cf file?

•  Is TCP port 25 (the port that sendmail uses) active?

•  Is the network connection down?

•  Is a firewall blocking the connection?

Other Diagnostic Information

For other diagnostic information, check the following sources:

•  Look at the received lines in the header of the message. These lines trace the route the message took as it was relayed, reading from the bottom up. Note that in the uucp network many sites do not update these lines, and in the Internet the lines often get rearranged. To straighten them out, look at the date and time in each line. Do not forget to account for time zone differences, and beware of clocks that have been set incorrectly.

•  Look at messages from MAILER-DAEMON. These messages typically report delivery problems.

•  Check the system log that records delivery problems for your group of workstations. The sendmail program always records what it is doing in the system log. You may want to modify the crontab file to run a shell script nightly that searches the log for SYSERR messages and mails any that it finds to the postmaster.

•  Use the mailstats program to test mail types and determine the number of messages coming in and going out.