Hope this helps you Nick:

For future reference, this appears at the bottom of every post to 
Lactnet.  I've highlights the parts that specifically refer to your 
request for unsubscription:

/_*Mail all list management commands to: [log in to unmask]*_/
COMMANDS:
1. To temporarily stop your subscription write in the body of an email: set lactnet nomail
2. To start it again: set lactnet mail
/_*3. To unsubscribe: unsubscribe lactnet*_/
4. To get a comprehensive list of rules and directions: get lactnet welcome

             ***********************************************

Archives: http://community.lsoft.com/archives/LACTNET.html
To reach list owners: [log in to unmask]
Mail all list management commands to: [log in to unmask]
COMMANDS:
1. To temporarily stop your subscription write in the body of an email: set lactnet nomail
2. To start it again: set lactnet mail
3. To unsubscribe: unsubscribe lactnet
4. To get a comprehensive list of rules and directions: get lactnet welcome