Edoardo Martelli wrote:
Hi Mike
Preferably it should run on windows (we're just not at home
on the *nix
platforms), have all it's config options in a sql database, provide
anti-spam and anti-virus out of the box, have a feature-rich webmail
client and be tailored for a small ISP.
Our specs: ~700 Domains, ~4000 Users
I'd use qmail-ldap on UNIX for it. It's as stable and as scalable
as you can get. The largest installation I know of has more than
3 million actual users on it in a large cluster. But then I'm biased.
The only thing coming close to it in scalability is Critical Path.
Both Yahoo Mail and Google Mail (Gmail) started off the qmail-ldap
code base. Rediff mail in India is running qmail-ldap with some
modifications. The last time I got information it was above 2 mio.
active mail accounts.
In any case I can give you three recommendations from 10 years
experience in this business:
a) chose an email system that uses maildir for mail storage.
Do NOT go with mbox or any other single file per user or
single file per mail server system. Just don't. Any also
never ever try to store the actual mails in a database.
b) use Linux or FreeBSD for your mail servers. Sun (Open)Solaris
acceptable too. Use UFS2 or EXT3 in journaling mode for storage.
Do NOT use Reiser or any of the other file systems.
c) use LDAP for user accounts. An SQL database not as good but
acceptable as well. It's just not really suited for it.
Do NOT accept black box user storage. If you do, you're locked
into that vendor forever as you can't export your user data to
move to a different system.
d) don't try to get a all-in-one system. Most likely you end up
with the worst or mediocre of everything.
e) if you seriously want to operate a mail platform you have to
build up some knowledge in-house. There is simply no way to
run a reliable and stable mail system with just a point-n-click
GUI and a 10 page quick introduction manual.
MS exchange? CERN uses it:
http://mmmservices.web.cern.ch/mmmservices/Help/?kbid=211030
http://mmm.cern.ch
The current version seems quite stable. But I'm just a user, I don't
know how it is to manage.
That's the problem. When an exchange server goes bad you're offline
for a couple of hours up to days. Exchange server stores everything
in one large linear database or log. Deleted mails are not really
free'd but just invisible. Every month or so you have to 'compress'
the message store to get the free space back. Compressing has to be
done offline so for two or three hours the server is unavailable.
When this message store goes corrupt, which it does from time to time
just by itself, then it takes hours again to run a repair. During that
time you're offline again.
Using Exchange server at an ISP is pretty much suicidal.
Interestingly email is still the core application of the internet.
User can go without the web for an hour but not without email. And
they use it 24x7. As an ISP you don't really have the option of
generous maintainance windows as the corporate guys have (from 19:00
to 06:00 plus weekends).
--
Andre
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