The Volvo 1800-120 Club Australia forum at Yahoo groups has been going since February 2000. 
Called the Volvo1800120oz group 

You can join this group and get all the messages as a 'Daily Digest' or as 'Individual Emails'. You can make that choice after joining. You have to first get a Yahoo ID (username and password) and then you can join the group. It is FREE.

Once you have your Yahoo ID, here is another excellent worldwide group you might consider joining and it's been running since mid 1998
1800list - Volvo 1800 Owners and Enthusiasts Group

With well over 2,500 members (including Irv Gordon) expect a lot of traffic from this one.