What probably happened is your e-mail program broke the activation key link (URL) because it thinks long lines should only be around 78 characters long or so. The whole activation key is there, you just need to reconstruct it from the e-mail. Here's an example for user John Q. Public, with the activation key parts in red:
From: IH Cub Cadet Forum [mailto:info@ihcubcadet.com]
Sent: Wednesday, September 1, 2004 12:00 PM
To: jqpublic@anywhere.com
Subject: Your user account application
Dear John Q. Public:
Congratulations! We are pleased to inform you that your application for a user account on this discussion board has been approved.
http://www.ihcubcadet.com/cgi-bin/forum/discus.cgi
Thank you for registering with our discussion board! In order to activate your new user account, simply click the following URL (if your mail program does not support clickable links, copy and paste the URL into your browser).
http://www.ihcubcadet.com/cgi-bin/forum/board-profile.cgi?action=registe
r4&u=jqpublic&k=TZGVOBAY
You chose a password when you applied for the account, and this is the password you should use to access the discussion board. As a reminder, your username and other registration information are shown here:
Username: Jpublic
E-mail Address: jqpublic@anywhere.com
Full Name: John Q. Public
Thank you again for your registration. We look forward to your participation on this discussion board.
The moderator who reviewed your application was: Admin
Notice how the activation key link was broken after action=registe and continues on the next line. It should read:
http://www.ihcubcadet.com/cgi-bin/forum/board-profile.cgi?action=register4&u=jqpublic&k=TZGVOBAY
What you need to do is either copy and paste each line into your browser, forming one continuous link, or use notepad (or other editor) to construct an unbroken link, then copy the entire unbroken link into your browser.
We apologize that you have to go through this, but unfortunately it's an issue with your e-mail client software, not our forum software.