Why does sendmail accept mail for every machine in my domain? How do I prevent this?
The default sendmail.cf file tell sendmail to acccept mail for every machine in your domain. This is almost always correct, because if mail is sent to a machine, you usually want it to accept it. However, there are some infrequent cases where you need to explicitly tell sendmail to only accept mail for itself (for example, if you set up a machine as a secondary MX, and you want it to only queue mail, not actually process it). In this case, you must modify ruleset 6 in the sendmail.cf. By default, ruleset 6 reads as follows: # special local conversions S6 R$*<@$*$=m>$* $1<@$2LOCAL>$4 convert local domain The LHS matches anything@anything.domain. The RHS tells sendmail to treat such addresses as local. Changing ruleset 6 to read as follows says to only treat items matching anything@machine-name as local: R$*<@$=j>$* $1<@$2LOCAL>$3 convert local domain Your $j variable must be set to $w.$m for this to have the desired effect.
