OSTicket is a good solution. Meets the above criteria.
osTicket, Freescout, Zammad or Request Tracker.
We use zammad as an MSP and absolutely love it. Feel free to ask any question
I need it for my internal IT ... we use ITOP but we all hate it.
It is important that people can create tickets via mail and answer tickets via mail and using LDAP Auth ...
I have 2 different support teams that cannot see each other's tickets. Both teams have different support email addresses.
Request Tracker
We used Issuetrak.
Depending on what you need, Znuny is great (we’re using it with ~1000 users)
OSTicket. It's free but also has a paid version.. The free version is not crippled at all. Works great. Been using it for years to support students at a college.
GLPI should met your requirements
Self-Hosted Main
A place to share alternatives to popular online services that can be self-hosted without giving up privacy or locking you into a service you don't control.
For Example
- Service: Dropbox - Alternative: Nextcloud
- Service: Google Reader - Alternative: Tiny Tiny RSS
- Service: Blogger - Alternative: WordPress
We welcome posts that include suggestions for good self-hosted alternatives to popular online services, how they are better, or how they give back control of your data. Also include hints and tips for less technical readers.
Useful Lists
- Awesome-Selfhosted List of Software
- Awesome-Sysadmin List of Software