I have a use case where users regularly include commas in their profile names (to include industry designations, for instance). Unfortunately this creates cases where user names aren't property properly escaped, which can result in malformed addresses with some MTA's.

In my case, I solved the issue with a quick hack to always enclose the name in double quotation marks, as that addresses the issue with the MTA in use in this situation (Postfix), and with our use-case.