[plug] mta differences

Cameron Patrick cameron at patrick.wattle.id.au
Fri Apr 16 19:13:51 WST 2004

Russ Powers wrote:

| I'm no expert but if you want a pointer until the guru's can help, I think 
| ~/Maildir with cur, new, and tmp are imap mailboxes and the ~/Mail is for 
| pop. 
| If you use an email program that's set up for imap it will look in the Maildir 
| directory. I think Mutt defaults to pop?

I think you're horribly confused.

Maildir-style mailboxes with each message as a separate file inside
cur/new/tmp are used by courier (including courier-mta [which sucks],
courier-pop3 and courier-imap) and qmail.  They can optionally be used
by exim, postfix and dovecot.  Normally they live in each user's home
directory as ~/Maildir - *not* in /var/mail.  Sub-folders of the inbox
are either stored as subdirectories inside ~/Maildir (courier and
dovecot) or as a separate hierarchy inside ~/Mail (kmail and mutt).

Mbox-style mailboxes (where each mailbox is a single file) are used by
sendmail, qpopper, and probably others.  They are the default for exim
and postfix.  qmail can be coaxed into using them.  Normally they live
in /var/mail/USERNAME, but sometimes go in ~/Mailbox.  Sub-folders are
stored as separate files inside ~/Mail (or possibly somewhere
completely different - there's very little standardisation here).

The advantages of maildir over mbox and vice versa have been discussed
endlessly with people swearing black and blue that their own preferred
format is superior.  They each have different advantages and
disadvantages.  I prefer Maildir.

Mbox is /generally/ easier to set up as it is the default for most
programmes; however it isn't supported at all by courier.  (Note that
courier will refuse to deliver mail to a user, and will refuse to let
you log in as a user unless ~/Maildir exists in that user's home
directory.  You have to create this manually for each; you can also
put it in /etc/skel so it'll be created automatically for new users if
you want.)

Both formats have been extended to store indexing information;
generally these extensions are understood only by the particular
programme which created them.

For the moment, I'd recommend using either exim or postfix as an MTA
(for ease of configuration); and dovecot for a pop/imap server.  The
default setup with these will use mboxes, unless a Maildir directory
exists in a user's home directory in which case dovecot will use that
and exim/postfix will deliver to mboxes in /var/mail as usual.  Urgh.

Note that the references above to kmail and mutt only applies when
they are accessing the mail folder directly; if they are accessing it
through an IMAP or POP server - even one running on the local machine -
then they will use whatever that server uses.

Clear as mud, everyone? :-P


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