I was sending out a meeting request through Microsoft Office Outlook today, and I got this warning message.
I used a comma to separate email addresses when I typed them. This is wrong, it is my fault, and I have to go back and fix it.
Outlook can clearly detect the problem, and the QA process revealed that people make this mistake often enough to warrant a specific warning. Yet, there is no way to make the tool actually fix this. Not only is there no "quick fix" button: you cannot find-and-replace within the "To:" field of the meeting request, so a user has to manually go in and replace the commas with semicolons. I guess that is the Microsoft Office usability engineers' way of training us to do things the Outlook Way (tm).