Over the past two weeks, I decided to try converting some of the mboxes I have for mailing lists to maildirs. Last time I tried to do it, I noticed an unacceptable delay when I started mutt. Not when I tried to load the largest maildir. That made me give up.
For fun (or was it profit? ;) ), I decided to try again. And again, I saw that delay. This time around, I ran strace on mutt, and I found out that my custom .muttrc was making mutt believe that every file in the maildir was an mbox. Fixing up my .muttrc made the delay go away. Now, I have start up times that are the same as with purely mbox setup, but opening up these maildirs takes up WAY less time. I’m talking fraction of second instead of 5-10 seconds.
I’m considering converting all but the spam box to maildir. I really don’t need thousands of extra inodes which I’ll never use anyway, but at the same time, I don’t mind having one gigantic file full of the spam messages (I keep them because I don’t manually check that no good messages got misclassified by spamassassin). I am going to probably tell XFS to reserve some diskspace for it, to prevent lots of fragmentation from the constant open-write-close syscall cycle.