[plug] mta differences

Craig Ringer craig at postnewspapers.com.au
Fri Apr 16 20:22:03 WST 2004

On Fri, 2004-04-16 at 17:02, smclevie at ozemail.com.au wrote:
> Hi all.
> OK I hope I am clear in my message ...

I must say I am having some trouble seeing what you're trying to do. I
understood from our private discussion that you simply wanted to provide
IMAP/POP access to an existing maildir mailbox. From what you say below,
you've tried to convert your entire system to using courier (including
the MTA - *ick*) - which suggests that perhaps I misunderstood your

I said that I thought Courier was alright for what I thought you wanted
to do - make a single existing mailbox accessible over POP/IMAP, and do
it quickly and easily. I would absolutely not recommend it for a "real"
mail server - there, I'd suggest Cyrus IMAPd or dovecot. Cyrus is
probably going to be outside your present ability to set up - it's not
friendly software - so something like dovecot would be a better choice.

> I installed (debian testing) the 'courier' suite of bits-n-pieces.


That'll install some or all of:


For your purposes, at least as I understood them last time, all you'd
want would be courier-imap and courier-pop. You'd then configure your
existing MTA (postfix, if I recall correctly) to deliver mail to Maildir
folders in the users' homedirs, and you'd be done.

> I created a few maildir directories inthe names of users with
> maildirmake /var/mail/johnny
> Then I looked at the 'directory' and it was present as a 'directory' when I did,
> ls -al 
> on the /var/mail directory.
> Then I send mail by,
> echo "To: johnny" | /usr/sbin/sendmail
> and when I went back to see the directory againwith,
> ls -al
> on the /var/mail directory I could see that the johnny 'directory' was now a file!!
> I could read the file with mutt and it showed an email.

/var/mail/$USERNAME is typically used for MBOX spool files. While I find
it more than slightly strange that the MDA apparently /removed/ your
custom-created maildir from there, it is normal to find mbox mail files
there. Maildirs are typically stored in the users' home directories.

> I can't download though to the mailbox...

I take it that means you can't access it using IMAP/POP? If so, that's
no surprise - your MDA isn't configured to deliver mail to the right
place in the right format, for one thing. 

Can you connect to the POP server? Authenticate? 

> When postfix is installed instead of courier 

Here I assume you mean 'instead of courier-mta', the part of courier
that might conflict with postfix. courier-imap and courier-pop should
live happily alongside postfix.

> I get a directory with 'new' and 'cur' etc.etc.  But I lose the ability 
> to send mail to a user on the local machine and I can't download into the 
> mailbox etc.etc.

I'm sorry, I don't understand this.

> This interaction between MTA's and Pop servers etc seems to be a rather 
> broken idea at this point in time, yes??

I think it's clunky and ugly, especially when extra stages (separate
MDAs like procmail, scanners like amavis or mailscanner, etc) get
involved. It's not that bad though, and I certainly wouldn't call it
"broken". The modularity is useful and important; it just needs cleaning
up a bit.

I detest the fact that a single mail delivery may fork four or more
processes, more because of the temp files written out and the disk
access caused than the actual forks. I'll be /much/ happier when I can
have persistent daemons sitting on an LMTP delivery pipeline, including
mail scanner, delivery agent, etc. That'd be /so/ much cleaner, and
we're getting there slowly, but there's a lot of ancient and/or
mail-server specific mail software out there that people want to work

There are also unfortunate limitations in some virus scanners etc that
require a new process to be launched each time. Additionally, some mail
server add-ons want to be able to immediately reject messages, something
you can only really do with MTA-specific plugins and interfaces so far.
There is work on an LMTP extension to allow someone on the other end of
the socket to reject messages, but I think it might be sendmail-specific
so far. *sigh*.

> ARE maildir mailboxes different between MTA's??


> Can courier-pop do multiple mailboxes or pick up a mailbox depending upon user??

It should look for a per-user mailbox by default. Please read the
courier-pop documentation to find out where it expects it, how to tell
your MTA to deliver there, etc.

Craig Ringer

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