====== Sendmail ======

==== How to create .cf file from .mc ====
It is always best practice to build .cf file from .mc
<code bash>
m4 sendmail.mc > /etc/sendmail.cf
</code>

==== 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//**alias database /etc/mail/aliases.db out of date**// \\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.

<code bash>
newaliases
</code>
OR\\
run 'make' in /etc/mail to update all databases\\
OR
<code bash>
sendmail -bi
</code>

==== Error Code 126 ====
Following messages you see in log and mail.
  * DSN: unknown mailer error 126
  * stat=unknown mailer error 126
  * runscript.sh: 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.

<code bash | sendmail.cf>
O ClientPortOptions=Family=inet, Address=192.168.1.22
</code>

NOTE : change 192.168.1.22 with your IP.


==== Clear queue ====

Check if you want to delete all mail.
<code bash>
mailq
OR
sendmail -bp
</code>

Now if you want to delete everything in queue just delete everything inside mqueue folder.\\
In CentOS it is located at **/var/spool/mqueue/**
<code bash>
rm -rf /var/spool/mqueue/*
</code>

If there is too many files to remove you better use option like xargs with find.
<code bash>
find /var/spool/mqueue -name * -print0 |xargs -0 -r -n100 rm
</code>