"MXlo means DNS resource records of the MX type that have a value of localhost."
We send mail on behalf of our customers (A) to their customers (B).
If (A) gets the email address for (B) wrong and the resultant email address is for a domain that is parked with a parking site (e.g. Sedo Parking) that uses MXlo the DSN my sytem sends to (A) reports that my system is misconfigured.
Does anyone know a way to better deal with this in sendmail or do I have to look at hacking my resolver libraries in some way ?
Suggestions received on comp.mail.sendmail from Claus Aßmann as follows:
Take a look at badmx and use it also for check_rcpt.
Write your own DNS map to look up NS, check whether it matches sedoparking.com and reject those addresses.
After further reading and experimenting I think this works...
FEATURE(`badmx')
LOCAL_RULESETS
SLocal_check_rcpt
R<$+@$+> $: <$1@$2> $| $>BadMX $2