Hello,
On Thu, 19 Jan 2017 06:30:24 -0500 John C Klensin wrote:
[snip]
>
> There are also some complex questions as to whether a server is
> ever permitted to refuse to accept mail with a backward-pointing
> address of "<>". Unless tied to either the identifying
> information in EHLO/HELO or the client's IP address, it would
> imply that the server never accepts bounce messages or MDNs of
> any sort. I have probably missed some cases, but think that
> would be a terrible practice and would certainly violate
> assorted assumptions of SMTP.
>
You're missing for example this:
http://slett.net/spam-filtering-for-mx/exim-sign.html
Which is something we use/offer here.
And the client IP address (RBL, locally listed) is another factor.
RCPT TO might be ineffective, but I don't see me exposing VRFY/EXPN ever.
Christian
--
Christian Balzer Network/Systems Engineer
chibi@??? Global OnLine Japan/Rakuten Communications
http://www.gol.com/
