> 25 it claims to be "tntkenya.com" and running "MDaemon".
MDaemon will fail a relaytest if you forge the sender to be
postmaster@<a valid domain for that MDaemon>
It will happily pass that email along. Even after applying
http://info.connect.com.au/docs/mdaemon/mdaemonsecurity.html it will still do that.
You CAN block the postmaster account, but that will get you listed in the rfc-ignorant.org database instead. The best idea seem to be to hammer the people behind MDaemon and get them to fix this.
Here is a link to a server running the newest MDaemon (with the security advice applied), that i tested. As you can see, it failed the test.