I've been using ARM devices for about a year now to host my website and e-mail and I thought it would helpful to start creating a series of tutorials to show people how to setup a Raspberry Pi for common server roles (web server, mail server, LDAP server, file server, DNS server).
My first one involves setting up a mail/groupware server (complete with webmail interface) using Citadel. Check it out at the link below.
Installing Citadel on RPi
http://www.ducky-pond.com/posts/2012/Ju ... el-on-rpi/