OT - Scalable email server solution needed

Duane Whitty duane at greenmeadow.ca
Tue Apr 11 15:57:47 UTC 2006

Duane Whitty wrote:
> Hi,
> My appologies in advance for the OT post.
> This probably more appropriately belongs on ISP@ but
> there doesn't seem to be much traffic there.
> To the point:  I'm about to provide hosting services,
> including but not limited to email, to a few local
> business.  Right now I have Sendmail configured
> and I was about to install Courier-IMAP.  My
> concern is future scalability.  I'm not sure sendmail
> is the right back-end MTA.  Right now Sendmail
> and Procmail will work fine I believe with the addition
> of an IMAP server.  But what about later on?
> I was looking at DBmail but I'm not sure just how
> much activity that project has so I'm a little leary,
> but perhaps that's unjustified?  So now
> I'm considering Exim or POSFIX.  The Sun Java
> Communications Server looks appealing but unless
> I misunderstood I don't have anywhere near the
> bankroll for that yet and it doesn't look like a good
> fit for a start-up operation anyhow.
> I like that POPular port and the way it uses proxies etc.,
> but it doesn't seem to support IMAP.
> Is there anyone on the list who might be serving many
> business customers each with many users who would
> be willing to share their insights or opinions on this?
> From my past experiences, transitioning from a low volume
> solution to a high volume solution, regardless of the application
> domain, is usually best solved by making the right choice in
> the beginning.  It would seem like an important marketing
> tool as well.
> If I am way of base here or missing something really
> important I'd appreciate the heads-up.
> Thanks in advance for any help.
> Sincerely,
> Duane

I would like to say thank you to everyone who has replied
to my query, both on and off this list.  Your input is much

I've read everyones answers and I have found them very
educational and helpful.

I have learned two things as a result of the help people have
offered.  First, everyone has their favourite mail solution, and
secondly, I am not in a position to decide which email system
is best for me at this time because I have not yet educated
with regards to the issues.

I believe that before I move away from the base email system
provided with FreeBSD, and the support and maintenance
attention it receives as part of the base system, I should
learn more about it.  I also need to learn more about it before
I agree to support an email solution for other people.  For this
reason I have decided to use an external provider, for the short
term, to meet the needs of those who have approached me for
hosting services.

I am basically taking my own advice.  In an earlier post on a
different thread I advised that people need to learn the tools
they are using before they can make conclusions about those
tools shortcomings.  If I can't make educated conclusions for
myself regarding Sendmail's strengths and shortcomings then
how can I reasonably expect to evaluate its replacement?  I
don't believe I can.  So I must learn the details of SMTP,
IMAP, Sendmail, mailfilters, and any other tools I will need
to use.  Then after using these tools for a while I will be in a
better position to evaluate them.

Right now I have a working installation of Sendmail that seems
reasonably secure.  It uses the DNS and after several tests it
appears to be closed to relaying.  I feel somewhat confident
about my DNS: it uses internal and external views, it doesn't
leak any internal information, it only does recursion for clients
on my private net, it only allows zone transfers to my authorized
secondary, and my secondary is geographically removed (somewhat).

With this foundation behind me I have started to do some more
reading.  I have read, from start to finish, RFCs 4234 (ABNF),
2821 (SMTP), 2822 (Internet Message Format), and 2476
(Message Submission).  I am currently reading the "Bat Book"
and the "Sendmail Cookbook".

 From the start I will be heeding the advice of several posters who
recommended using maildir format.  To implement that I will be
using Procmail, at least to start, as soon as I learn a little more
about Sendmail.

I hope no one feels I have wasted their time and I would truly
appreciate further comments that you believe might aid me on
my path.


Duane Whitty
duane at greenmeadow.ca

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