gzt: Cool. Is it excluded from quote blocks? That could get annoying.

freitasm: Testing with @sbiddle, @tonyhughes, @scottjpalmer... Did you get this message? [Again?]

danielfaulknor: Adding matching whitespace on either side takes care of the email matching, but will mean that if people miss a space it won't match

\s\@(\w+\b)\s

OR 

\s\@(\w+\b)

Depending on if you want to match whitespace on both sides or just infront.

If ASP VBscript doesn't support \s for whitespace, you can escape a normal space too with "backslash space"

• Notifications aren't sent out if edit a post - adding a @ AFTER you posted won't trigger the emails. In this case is better to add a second reply for example
• Early on we accepted usernames with non alpha/number characters, so there's a nic.wise for example (Hi Nic!). To make sure we filter bad stuff the function will obviously look for alpha/numbers that form a valid user name, using the same validation function as the registration page. So nic.wise will never get a notification...
• More than one mention of a username in a single post triggers one email notification only