Maildir vs mdbox? should i migrate?

Operating System & Version
operating_system_name: cloudlinux operating_system_version: 7
cPanel & WHM Version
cpanel_and_whm: 11.92.0


Active Member
Dec 13, 2013
cPanel Access Level
Root Administrator
Hi happy new year to everyone, i currently have one whm server with almost 500 users, they all have like 30gb-100gb mail accounts, should i change from maildir to mdbox? which are the real advantages? of course i run everyday a backup offsite.

thank you


Well-Known Member
Nov 9, 2001
cPanel Access Level
DataCenter Provider
Here is a little doc from WHM: Mailbox Conversion | cPanel & WHM Documentation

To me the biggest question is backups. maildir stores each email received (or sent) in it's own file. mdbox is one big file containing many messages (like an Outlook .pst file). If you are running incremental backups it's going to be a lot easier/quicker to backup maildir (you'll only pick up the changes) vs mdbox (you have to backup the while file + any new ones created).

Your going to end up with less corruption with maildir (if you have any issues). The worst thing that can happen is that the Dovecot indexes get messed up and those are easy to rebuild. If a mdbox file gets corrupted, it's prob. going to be more difficult to fix.

The downside of maildir is the WHM transfer system. Rsync can take a long time with a lot of little files and that's exactly what maildir is.

My 2 cent!