Jan P. Kessler:
> 1. Will check_sender_mx_access lookup an a record if there is no mx
> record for a given sender domain? I guess it won't as there's
> reject_unknown_sender but I'd prefer to be sure.
It looks up MX records. As with many other Postfix features, there
is no access control on information that does not exist.
> 2. Is there a maximum number of mx records that will be checked by
> postfix? Are there any standards requiring or recommending this? Just to
> prevent trivial DoS attempts by setting up domains with hundred of mx
> records.
People do occasionally set up domains with lots of records. Postfix
2.3 and later will accept DNS replies of up to 32kbytes. However,
the Postfix SMTP client will use only a limited subset of those
records.
Wietse
