Hello,
it would be very nice if an unknown user can create tickets via Mail.
Why?
If you want to use tuleap as a Ticketsystem in the Help Desk you don't know from where are the tickets come. Eg: an other institute has a problem with our mailserver or something is misconfigured (eg a problem with a link on the website) he/she/it would write a mail to
support@example.com which ends in tuleap.