Comments on: Mbox vs Maildir: Mail Storage Formats

By: Scott

Scott — Sat, 27 Dec 2008 11:08:16 +0000

Thanks for the indepth explination of the two formats. I’m using Maildir for my email server, however (I’m using postfix) the default setup uses mbox. I wish I had have found your site a little earlier!!! and the mb2md.pl (well I have it now!!!)

By: consultant

consultant — Mon, 02 Jun 2008 16:50:59 +0000

Hi Timo,

I’m very honored to hear from the author of Dovecot. Thank you very much for your comment, I’ve updated the text above.

1. Corrected the mbox delete algorithm.
2. Added the algorithm for the mbox and maildir search.
3. Discussed the advantages and disadvantages of searching when using mbox and maildir.

By: Timo Sirainen

Timo Sirainen — Mon, 02 Jun 2008 16:08:04 +0000

1) mbox’s “Rewrite the whole mailbox file, leaving out the mail to be deleted” isn’t exactly right. The data is moved within the file, so deleting mails from the beginning of the mbox causes more data to be written than mails deleted from end of file. So deleting the last mail(s) wouldn’t cause any data to be written at all, just a ftruncate() call.

2) Maildir is missing one disadvantage (mbox’s advantage): Maildir is slower when all files have to be opened (e.g. searching a message). It’s faster to read through one big file than open and read lots of small files.

By: Francis

Francis — Sun, 30 Mar 2008 03:03:59 +0000

Thanks for the info. Will test that once I finalize the setup i’m putting up using the guide for CentOS 5 on this site.

By: consultant

consultant — Sat, 29 Mar 2008 14:02:56 +0000

I do. I used mb2md.pl

I initially configured my mail server to use mbox. The users encountered locking problems when they began to check their mails so I immediately converted the mailboxes to maildir using the script above.

By: Francis

Francis — Sat, 29 Mar 2008 08:26:49 +0000

I’m planning to migrate from a mail server running sendmail using the mailbox format, to a server configured using the guide in this site with users from ldap running postfix. Is there a way to migrate from the old mailbox format to the new maildir format without loosing data?

I found some scripts on the net. Anyone has experience using these things?