I have a mail server (Qmail) and just tried to install mdadm to monitor the raid arrays via Yum and it tried to install exim. Is this correct? I guess that it is looking for an MTA so why is it not finding Qmail (linked to /usr/lib/sendmail). One possibility is that I used yum to actually uninstall sendmail, but installed qmail from source as it needed patching.
Any way out of this apart from installing mdadm from an rpm with no deps/
It won't find qmail because qmail isn't in the rpm database, so yes... mdadm is doing the right thing by trying to install a mailer. It's linked as a dependency to notify admins if an array has issues.