Yum command to downgrade packages

Sure it seems weird...

Can you boot in rescue mode from the installtion CD ?

If yes, you could use the yum command from the rescue system to reinstall yum on the system...

Yum should have the "installroot" option available so...

Should I try to remember how to do it ?

You could do something similar to this.

for i in `grep -i "someuser@recipientdomain.com" /var/log/maillog | awk '{print $5}'`; do grep -i $i /var/log/maillog; done

This will grep out the line for the user you are looking for, then select the 5th item on the line (seperated by spaces iirc). Then for each message ID in that list, will then grep for the lines containing the message ID's.

If you want to remove the : from the end of the message ID, you can do something like for i in grep -i "someuser@recipientdomain.com" /var/log/maillog | awk '{print $5}' | sed 's/\://; do grep -i $i /var/log/maillog; done

Hope that helps.