Archive for 'Sendmail'

Printing the entries in a sendmail queue

Since I began managing sendmail installations 8-years ago, I have used the mailq command to print the entries in the sendmail queue. While reading through the bat book to find the root cause of my sendmail DNS problems, I came across sendmail’s “-bp” option: $ /usr/sbin/sendmail -bp /var/spool/mqueue is empty Total requests: 0 This provides […]

Optimizing sendmail smart hosts

While debugging an issue last week, I noticed some odd behavior when the Sendmail Smart host configuration directive (DS) was used. Smart hosts allow nodes to delegate mail delivery services to upstream devices, alleviating the need to run a full blown mail relay on each host. Smart hosts are configured with the Sendmail MC SMART_HOST […]

Binding sendmail to the loopback interface

The sendmail SMTP server comes with the vast majority of UNIX Operating systems, and is configured to listen for new connections on TCP ports *.25 (SMTP) and *.587 (MSP) by default. For workstation and servers that aren’t responsible for mail delivery, this can cause chaos when a new sendmail exploit is released into the wild. […]