Sorry, but RT is still the least hateful ticket system you can get for free.

Gitlab supports issues by email and by website. It's a git server, but you didn't specify you wanted it to be purely issues :-)

We have a large number of non-technical managers able to use it to file issues etc if you give them the URL to the issues page.

IDK, have you MET @davepage_mcr

Pfft, isn't even codethink green