Postfix(MTA) appln corrupt ( OS: RHEL4)

If your postfix (MTA) stopped working or corrupt and not sure how to upgrade or downgrade it for better performance???

Here follows the solution for that :

step 1 : Query installed appln to know version details ( use following command )

command # rpm -qi postfix

step 2: Search for updated RPM of Postix ( if have subscription use www.rhn.redhat.com) and download to local machine

step 3: Query to list postfix related files using following command as a root

command# rpm -ql postfix

step 4: better backup files ( output of above command ) which are essential like, Configuration files /etc/postfix and mail queue /var/spool/postfix using command {cp -a source destination}

step 5: simulate RPM package installation before installing to machine. This will help to identify dependances error and file conflicts error.

command # rpm -Uvh --test postfix-2.2.x-RHEL.rpm

step 6: If found no error on above command , Now you can go for installing RPM using following command

command # rpm -Uvh postfix-2.2.x-RHEL.rpm

step 7 : To release mail queue built on the system when MTA was corrput. we need to requeue mails to flow again by following command

command # postsuper -r ALL

step 8 : Give a look on maillog to check for mail delivery to domain.

command #tail -f /var/log/maillog

Note : if you want to downgrade MTA, use this command instead of step 5 and rest of steps are same.

command # rpm -Uvh --test --oldpackage postfix-2.2.x-RHEL.rpm

command # rpm -Uvh --oldpackage postfix-2.2.x-RHEL.rpm