[CentOS] Re: Mail server setup for small ISP

[Ugo Bellavance]

Bill Campbell wrote:
> On Thu, Jan 03, 2008, Ugo Bellavance wrote:
>> Hi,
> 
>> I will probably have to design an e-mail (and other components)
>> infrastructure for a small ISP soon (WISP).
> 
> See my previous post on sizing mail servers.  The setup there is
> in use at several of our regional ISP customers, and has been
> very solid.  It's a design that has evolved since we started
> building and selling systems for ISPs in 1994.

Ok, but I can't seem to find it.  Can you send me the link (see the 
'archived-at' header in the message).

>> I'm doing some research to determine which components would be best to
>> offer e-mail services to their client and allow the staff to manage
>> accounts easily.
> 
> There are various tools available to do this.  I have set up very
> restricted webmin configurations so the support people at the ISP
> could do the necessary things easily with minimal chance of major
> screwups (after I've patched some things in webmmin that allowed
> it to remove /home when somebody typed in a bad directory :-).

Makes sense, but hard to integrate with billing, for example. But could 
do.  I'm trying to think long-term, while avoiding spending too much time/$.

>> I usually use virtual machines a lot for isolation and easy backups and
>> migration (when a hardware node is underpowered, it is easy to migrate one
>> or more virtual machines to another hardware node easily).
> 
>> I have looked at iSCSI and drbd for high-availability of the storage:
>> http://www.pcpro.co.uk/realworld/82284/san-on-the-cheap/page1.html.
> 
>> This looks like it should be doing a great job of high availability
>> storage.
> 
>> For mail server, I guess I should look at an MTA and IMAP/POP server that
>> supports LDAP and/or MySQL for users.  Postfix should be a good choice for
>> MTA, as I know it (at least a little, but I know sendmail better).  For
>> IMAP/POP, I'm not sure...  Would dovecot be sufficient, or should I try
>> cyrus.  I'd rather use components that are available for base or extras
>> repository (or rpmforge).  I think that squirrelmail and horde would do a
>> good job for webmail.
> 
> The systems we build have postfix/amavise/clamav, courier-imap,
> and usually horde/imp for webmail.  I personally don't like Cyrus
> as I prefer to use standard Maildir which allows easy clustering
> for mail delivery and IMAP/POP access.

Ok, what do you mean by easy clustering?  Over GFS?  What make it hard 
to cluster in Cyrus?

>> There shoudn't be any troubles having some redundancy for DNS, web servers,
>> mtas, but what about IMAP/POP? linux-HA?  MySQL replication should be
>> enough, I guess.  Or maybe linux-HA as well.  I wonder if I should add GFS
>> to the mix to have multiple IMAP/POP servers use the same storage.  Or
>> maybe IMAP proxies?
>>
>> 	Any insights welcome :).
> 
> I hope you're not charging your client for your learning curve.

Of course not.  Actually, I'm doing research even before having the 
requirements, to know what is possible as soon as possible, once I have 
the requirements, and to be able to discuss with the potential client 
without having to say "I'll have to research on this" every 5 seconds.

Thanks a lot for your help :).

Ugo