Gregory's Server
@abcdw Bugzilla is a good option, even though I personally prefer redmine (https://www.redmine.org), probably out of mere convenience (can’t imagine Bugzilla not being on par with it); it supports creating issues by email, organising issues in projects, has a “good enough” VCS integration, following issues via RSS and so on.
@thees One of the "downsides" of bugzilla that it can't create issues from anonymous users like redmine https://www.redmine.org/projects/redmine/wiki/RedmineReceivingEmails#Enabling-unknown-users-to-create-issues-by-email
However, I think it can be work arounded by some REST API glue code.