> FEATURE(`require_rdns')
> ^^^^^ This feature only ensures a reverse exists, you dont want to make a
> match for forward and reverse being the same, or you wont get mail from
> most places, since hosting companies don't configure their mail servers
> this way (nor should they).


Why should hosting companies not do this ?

And where did you learn about these features... I have bought the
sendmail cookbook but as I'm looking now it goes up to 8.12.10... :
[ is there any newer books ?