http://en.wikipedia.org/wiki/Jon_Postel#Postel.27s_Law
"Be liberal in what you accept, and conservative in what you send" Software, and the way people configure it, should be RFC compliant but reality often falls short of this ideal. On 13 May 2013 10:01, 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 > >
