Summary:
Normally not a big deal but it does have side effects we discovered today. A user couldn't create new comments because they were using 'admin' as their worker address instead of 'admin@localhost'.
Steps:
1) helpdesk setup, workers
2) create a new worker and fill in a username instead of an e-mail address (no @domain)
This may also be an issue during the install period, but I have not got a chance to confirm yet.
If, or when, it's fixed in the installer, we can close this really old issue where it was written up originally (this was back in the early 4.x days). CHD-626