Hello Nikolas, not everybody respects the RFCs. A time ago, I enabled this setting on a production machine, however lots of legit mail was blocked due to this. So I mailed the postmasters of such domains to be RFC compiliant but many of them not even responded and some were really angry. So the question is - do you want your users to be able to communicate or you want to fight with administrators that have never read the RFCs...
On Mon, May 13, 2013 at 10:01 AM, Nikolas Kallis <n...@nikolaskallis.com>wrote: > Hello, > > > > Postfix's documentation quotes for 'reject_unknown_helo_hostname'**: > "Reject the request when the HELO or EHLO hostname has no DNS A or MX > record." > > > Under '3.6 Domains' of RFC 2821 it says: > > "Only resolvable, fully-qualified, domain names (FQDNs) are permitted > when domain names are used in SMTP. In other words, names that can > be resolved to MX RRs or A RRs (as discussed in section 5) are > permitted, as are CNAME RRs whose targets can be resolved, in turn, > to MX or A RRs." > > > I have seen in Postfix's documentation that it caters for 'home-grown' > software for some attributes. Catering for POS software isn't being > standard compliant. > > As it is a requirnment for a RFC 2821 compliant SMTP server to have a > resolvable A and MX record, then 'reject_unknown_helo_hostname' shouldn't > even exist, instead Postfix should be rejecting the connection all together. > Assuming this is why 'reject_unknown_helo_hostname' exists; the > home-brewer should get his software right, instead of expecting others to > make exceptions for his lack of skill. > > If Postfix was compliant with RFC 2821 in this respect, I wouldn't have > had to of wasted half my day. This is the whole point of standards. > > > > Regards, > > Nikolas Kallis >
