In the first year of the implementation the council has spent about £60,000 on a Suse Linux-based e-mail system for 7,500 users, at a cost of £8 per user.
Richard Heggs, the systems analyst responsible for the council's e-mail system, said users are now sending 300,000 e-mail messages a month, a 400% increase on 2002.
Meta Group vice-president Ashim Pal said, "A typical enterprise e-mail system costs £80 per user per year."
Unlike feature-rich commercial e-mail servers such as Lotus Domino and Microsoft Exchange, Pal said open source e-mail is more basic, and usually lacks collaboration software such as shared calendars.
Nottingham's e-mail system uses two multi-processor Xeon servers, one configured with two processors and 2Gbytes of memory, the second is a four-way with 4Gbytes of memory and connects to a storage area network.
The open source software used includes Suse Linux Professional and the Exim simple mail transfer protocol e-mail server. If this architecture was replicated across local and national government, the public sector could potentially save millions of pounds.