[SATLUG] Help needed setting up a mail server

[Brad Knowles]

On 11/28/07, Chris Lemire wrote:

>    Mailman (I'm still trying to figure out what I am going to use this for,
>       but I think it would be very cool and useful to learn.)

There are some specific issues with Mailman and fetchmail, and I'd 
encourage you to take a look at the FAQ Wizard at 
<http://www.python.org/cgi-bin/faqw-mm.py> and also search the 
archives of the mailman-users mailing list (as discussed in FAQ 1.18 
at 
<http://www.python.org/cgi-bin/faqw-mm.py?req=show&file=faq01.018.htp>).

>  Here are my questions.
>
>    How can I know if I need SASL when setting up Postfix?

If you're going to be doing anything with authentication, you're 
probably going to want SASL.  You'll have to choose between Cyrus 
SASL and Dovecot SASL, however, and they are not mutually 
interchangeable (Dovecot SASL seems much simpler to set up, but Cyrus 
SASL is much more capable).


Setting up SASL can be a bitch.  I've been administering Internet 
e-mail systems since the very early 90's, both large and small.  I've 
been involved with postfix and more or less active in the postfix 
community since '98, back before it was officially released and was 
still being called VMailer.  But at each of those places, I never had 
to worry about the authentication system -- that was already in place 
and I just connected to whatever they had.

At one of the open source projects I help support, I'm in the process 
of rebuilding the entire mail system, and I've been trying to 
configure SASL.  But with all my years of experience, I haven't been 
able to wrap my head around it.

I recently attended the LISA'07 conference in Dallas and paid large 
sums of money to take tutorial sessions, including some from Ralf 
Hildebrandt and Patrick Koetter (authors of "The Book of Postfix", 
which I consider to be the best reference available on the subject), 
but most especially including their half-day tutorial on SASL.  And 
my eyes glazed over, and I still haven't been able to wrap my head 
around it.

>    How can I know if I need SMTP Authentication?

If your upstream MTA requires it, then you need it.

>    Do I need it because gmail uses it even though I will be relaying
>         mails to my internet

If you're sending them directly, or passing them on to your ISP, then 
you may not need SMTPAUTH.  If you want to send them via gmail, then 
you probably will.

>    Should I configure Postfix to use mbox or Maildir format?

That depends on your IMAP/POP server, and what other choices you make.

If you're going for simplicity of operation and supporting both local 
and remote clients accessing the same mailbox, then you might want to 
look at the UW-IMAP server, which supports a wide variety of mailbox 
formats.  However, Maildir is not one of the formats it officially 
supports, so you'd need an unofficial third-party patch.

If you know that all your local clients can support Maildir and you 
want an IMAP/POP server that also supports Maildir, then you should 
check out Courier-IMAP and Dovecot.  Of course, classic Maildir has 
certain performance issues, at least some of which are addressed by 
using Maildir++ instead.  If that's an option for you, then you'd 
need to check into which IMAP/POP servers support Maildir++ as 
opposed to the original Maildir.

If you're going to be using remote-only clients (i.e., they only use 
IMAP or POP to access the mailbox, as opposed to directly accessing 
the filesystem), then the most powerful and scalable option would be 
Cyrus -- it includes it's own mailbox-directory type message store, 
but it also includes things like Berkeley DB indexes on the messages, 
which can greatly speed up many types of operations.  But then Cyrus 
may be overkill for your current requirements.

>    Why should I configure it to use one or the other?

Different programs support different formats.

>    Does Fetchmail use mbox or Maildir?
>    Which one does it use by default?

It's not clear to me what mailbox format fetchmail uses internally, 
but from looking at the main web page at 
<http://www.fetchmail.info/>, I find the following paragraph of 
interest:

	Fetchmail retrieves mail from remote mail servers and forwards
	it via SMTP, so it can then be read by normal mail user agents
	such as mutt, elm(1) or BSD Mail. It allows all your system
	MTA's filtering, forwarding, and aliasing facilities to work
	just as they would on normal mail.

As such, it's not clear to me that it really matters what type of 
mailbox format you use on either end.

Internally, it appears that it might use mbox, at least from what I 
can determine by looking at the Fetchmail FAQ at 
<http://www.fetchmail.info/fetchmail-FAQ.html>.

>    Should I configure Postfix to use the same as Fetchmail?

If you don't care what mailbox format fetchmail uses internally, then 
you would appear to be free to choose whatever type of mailbox format 
you prefer.

-- 
Brad Knowles <brad at shub-internet.org>
LinkedIn Profile: <http://tinyurl.com/y8kpxu>