Nathan Ollerenshaw wrote:

Hey Nathan,

I think that your ideas look pretty good. Here are my notes:

For the MTA, I would recommend looking at qmail. http://www.qmail.org

It would be nice if you could leverage your account information into an LDAP capable directory server like Netscape Directory Server. Oracle's Oracle Internet Directory (OID) would probably work, as well. A number of email related products support authentication through LDAP, which would be one less worry for you. Check out this article about LDAP servers: http://www.nwfusion.com/reviews/2000/0612revoracle.html?nf Netscape Directory Server is supposedly still the performance king.

Qmail-LDAP (just an LDAP patch against stock qmail) works great, and clustering is a no-brainer. http://www.nrg4u.com

Check out Life With Qmail (excellent documentation for qmail). http://www.lifewithqmail.org Also, there is a brief comparison of MTAs there. http://www.lifewithqmail.org/lwq.html#comparison There is a Life with Qmail-LDAP page, as well. http://www.lifewithqmail.org/ldap/

I use this setup for my office: LDAP Server - Netscape Directory Server 4.12 Mail Transfer Agent - Qmail with LDAP patch Mail Delivery Agent - Maildrop IMAP/POP Server - Courier IMAP/POP Server Webmail Server - SQWebMail

All account information is stored in LDAP, and everything authenticates to LDAP without a problem. There is no shell access, and all mail is stored in a "virtual user" environment.

Maildirs are NFS mounted to the mail server(s) from a Network Appliance F720. I only have one production mail server, but I plan to incorporate one more for high availability. This is only serving a small office, so the load is very small. I have an Extreme Networks Alpine 3808 switch for my network. It has some Server Load Balancing code from F5 in it, which I will probably use to cluster these machines.

You should definitely check out F5 for server load balancing: http://www.f5.com/

If you really want to save some cash, check out Network Appliance for your NFS servers. Seriously, these servers smoke Sun servers in NFS performance. http://www.netapp.com/ Check out the benchmarking at, http://www.spec.org/osg/sfs97/

A 16 Node (16 CPU) cluster of NetApp 840s using NFSv2 over UDP get 250,573 ops/sec!!!

These NetApps are made to serve files over NFS. They also have many other great features like snapshots, ability to support Unix and Windows shares on the same files, and clustering. They use a unix-like microkernel built specifically to make these boxes "network appliances." They also use the WAFL file system, a journaled file system built specifically for their hardware configurations. I'm sure that you could get more space and NFS performance using a NetApp filer over a Sun server.

Also, you could throw some cheap intel hardware with FreeBSD on it behind a server load balancer and in front of a cluster of file servers to do all the smtp, pop, imap, etc. work. This would cut costs considerably. You can build a beefy Intel machine for a fraction of the cost of a Sun server.

If you are checking out the commercial market, take a look at Stalker Software's Comunigate Pro. It looks to be high speed/low drag. It can support millions of users and has support for everything (web interface, ldap, acap, imap, pop, virus scanning, clustering, etc., etc...) It has licensing costs on the page. http://www.stalker.com/default.html

I like our current setup. All that I'm missing is a good gui interface to tie it all together. I'm thinking of putting something together in Java or PHP to manipulate the LDAP tree that's more suitable to me. I'm also looking at Courier as a replacement for Qmail. It's a little tricky getting all of this stuff together, but it's all open and fairly customizable.

Just some things to think about ;)