Mailsetup Migration from mailcow to mailu

Rebuild the whole mail setup to be based on mailu

assigned to @void

requested review from @3d

requested review from @jabertwo and removed review request for @3d

removed review request for @jabertwo

added 17 commits

• 31d43a1a...bf8720e5 - 16 commits from branch master
• f7574841 - Merge branch 'master' into 'test-mailu'

Compare with previous version

merged

mentioned in commit b0657d3b