There is an mtools mailing list at <firstname.lastname@example.org> . Please send all bug reports to this list. Note: You must be subscribed to the list in order to be able to send comments.
To subscribe to these or any GNU mailing lists, please send an empty mail with a Subject: header of just subscribe to the relevant -request list. For example, to subscribe yourself to the mtools list, you would send mail to <email@example.com>. Or you can use the mailing list web interface.
Announcements of new mtools versions will also be sent to the list. There also exists an archive of the mailing list (currently only accessible to subscribers).