The best replacement for mailman is phplist.

The best alternatives to mailman are rated as following:
★★★★★  phplist
★★★★  postman
★★★★  cat
★★★★  majordomo
★★★  milkman
★★★  listserv
★★  sympa
★★  mail man
★  google groups
★  angry cat
★  ezmlm
★  dada mail
★  milkman youtube
  postmaster
  milkman barats and bereta

Your alternative for mailman is not listed? Suggest!
Speaking about mailman, one probably shouldn't forget about angry cat.

Other search terms related to mailman and their ratings are:
★★★★★ angry cat
You have in mind a companion for mailman and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of mailman in all years. Click on graph for more.
mailman
phplist
postman