Error messages due to extra comma in address?

[Chris Crowley]

I have seen this error message twice from the horde problem report mailer. I
am currently speculating that the users mis-typed their email address and
added an extra comma.

Have others seen this behavior? If so, have you traced it to imp, or to
sendmail? Any clever fixes? ('s/,$//') ?

MISSING_MAILBOX_TERMINATOR@.SYNTAX-ERROR,
   UNEXPECTED_DATA_AFTER_ADDRESS@.SYNTAX-ERROR

TIA,
Chris