One crucial question that you did not ask was this one: Can Debian distribute a modified version of IMAPD *and give everyone permission to distribute their own secondary modified versions of the Debian version*?
"Yes" would mean that people who get the Debian version would be allowed to redistribute modified versions of *that* without communicating with either a representative of Debian or the U of W. If the answer is yes, then a Debian modified version of IMAPD could be included in the official Debian GNU/Linux system. Otherwise, it could not be.
