My morning:

john@smarthost:/var/log# ls -1 |wc -l
450895
john@smarthost:/var/log# rm -f mail.err.*
-bash: /bin/rm: Argument list too long
john@smarthost:/var/log# rm -f mail.err.1.*
john@smarthost:/var/log# rm -f mail.err.2.*
john@smarthost:/var/log# ls -1 |wc -l
393723

If you understand this, I'm sorry.

(How it happened: Runaway logrotate, triggering on "mail.*" not "mail.log, mail.err, mail.info")