fix: move user setting to mail server, add test #328

All 22 tests pass in 3m 26s

22 tests +1 22 ✔️ +1 3m 26s ⏱️ + 1m 38s
  4 suites ±0   0 💤 ±0
  4 files ±0   0 ❌ ±0

Results for commit a81b227. ± Comparison against earlier commit d4f7595.