A side question : is it (I guess not, but in case) possible to exclude a specific version? I mean, I will downgrade to Exim 4.93, then exclude Exim 4.94 only... And yum will automatically well update to Exim 4.95 when it will appear in a repo?
Yes, of couse. You can replace
Code
exclude=exim*
with the exact packagename or parts thereof. The "star" is just a placeholder, so all packages that starts with "exim" are excluded.
But excluded packages won´t update to whatever while blocked.
You can also use yum versionlock to block the currently installed version from being upgraded. Here is a good article about this: