Nice catch, Jade D.
If your domain is in a broken state I'd remove the account from your C:\SmarterMail\Domains\<The Domain>\accounts.json file. Make sure SmarterMail isn't running while you do this.
I'll put in a task to add "aux." (and others) to our validator for email addresses. This will prevent SmarterMail from even trying to create that user.
Matt Petty
Senior Software Developer
SmarterTools Inc.
www.smartertools.com