Email Server

• Norman - Norman Mailer, of course
• Cliff - mailman from Cheers
• Newman - mailman from Seinfeld (particularily if your mail server is a bit of a pain in the ass)
• Pat - Postman with cat
• Hermes - messenger of the Greek Gods
• Mercury - messeger of the Roman Gods
• Echo - Greek nymph, cursed by Hera to always repeat another's voice.
• Hedwig - Harry Potter's mail owl
• Huginn or Muninn - two ravens that travel the world bearing news and information they have collected back to the Norse god Odin.
• Mr. Beasley - mailman from the comic strip Blondie.
• Pigwidgeon - Ron Weasley's mail owl
• Letter
• Frisk - Could be used for AV or Spamfilter.
• Post
• Carrier pigeon; Messenger pigeon; Homing pigeon; Homer; Pigeon

At one time Mindspring used the names of former postmaster-generals. That however led to quite a few that no one knew how to spell.