In access(5), the documentation says (in regard to HOST NAME/ADDRESS PATTERNS):
domain.tld Matches domain.tld. However it fails to indicate what this actually *means*. This seems to be a bit of a documentation failure. Which one of the following is it? (a) Match an IP address whose reverse DNS matches 'domain.tld'. (b) (a), with a subsequent forward-lookup to check it isn't a fake reverse DNS entry. (c) Match an IP address which is listed as one of the results for an A-record lookup of 'doman.tld'. (d) Something else. I have a situation where I have a DNS record 'foo.example.com', which resolves to multiple A records. I want to allow mail transactions if and only if the incoming connection is from one of those IP addresses. Is this possible with Postfix, and if so, how?