Keith Moore wrote:
Start by writing a paper about "BCP of SMTP operation".
(1) Don't block empty envelope from:
(2) Don't say ok to a recipient address if you are not 100% sure you can do
any others that folks want to contribute?
Yes, certainly. Like you, I noticed a substantial increase of the blocking of
empty envelope from addresses, which worried me.
Apart from that, I noticed during the last couple of months (doing postmaster
duties for a company) that more and more MX-listed systems are misconfigured and
reject mail with SMTP 5xx status responses telling that they won't relay for
I can easily show a number of these rejections. The annoying thing is, that when
I try to send mail to postmaster(_at_)domain or postmaster(_at_)Mx-listed host,
messages also are rejected with the same message.
So please ad:
(3) don't reject mail if you are listed as MX host
(4) always support postmaster(_at_)domain, for all domains for which you send
BTW: I wouldn't name it a BCP, since most of the above items are clearly stated
as requirements in RFC's. So I would call it an informational RFC (or what's the
name for such an RFC?), like there is also an RFC stating common configuration
errors in DNS/Bind (I don't remember the RFC number, but I believe Piet
CWI has contributed to it).