Postmaster (MTA)
Postmaster is a mail transfer agent for Unixoid operating systems written in Haskell .
function
In contrast to common mail transport agents, its structure can be compared with the Xmonad window manager written in Haskell : Postmaster is a program library that provides functions that are required for developing an MTA. The server administrator writes his own MTA in Haskell. This is then responsible for the administration of the accounts.