User Tools

Site Tools



How to create .cf file from .mc

It is always best practice to build .cf file from .mc

m4 > /etc/

Rebuild aliases

when you modify /etc/mail/aliases.
Possibly you see following message.
alias database /etc/mail/aliases.db out of date

Simply run following and will fix it.


run 'make' in /etc/mail to update all databases

sendmail -bi

Error Code 126

Following messages you see in log and mail.

  • DSN: unknown mailer error 126
  • stat=unknown mailer error 126
  • Permission denied
  • 554 5.3.0 unknown mailer error 126

It is because script you call to catch email OR execute when received has permission issue.
Simply set permission on that script to “Sendmail Default User” could be 'daemon' or 'mailnull'.
the names i have used those are i came across till now. so chances are there you see something diff.

Whole path need to be executable by that user.

How to change outbound IP

to change outgoing IP on your sendmail server.
change following variable.

O ClientPortOptions=Family=inet, Address=

NOTE : change with your IP.

Clear queue

Check if you want to delete all mail.

sendmail -bp

Now if you want to delete everything in queue just delete everything inside mqueue folder.
In CentOS it is located at /var/spool/mqueue/

rm -rf /var/spool/mqueue/*

If there is too many files to remove you better use option like xargs with find.

find /var/spool/mqueue -name * -print0 |xargs -0 -r -n100 rm
sendmail.txt · Last modified: 2020/08/10 02:35 (external edit)