--On 15 January 2010 15:15:42 -0600 Don Lee
<spfdiscuss(_at_)caution(_dot_)icompute(_dot_)com> wrote:
--On 14 January 2010 14:52:40 -0600 Don Lee
<spfdiscuss(_at_)caution(_dot_)icompute(_dot_)com> wrote:
On the one hand, CNAME for HELO is all too common (and accepted - wrong
though it may be), but HELO that does not resolve, or does not have
port 25 open on the resolved IP is more and more commonly the reason
for mail from that server being rejected.
There's no reason that my sending mail server should have port 25 open.
Many sites separate their outbound and inbound servers. Sender
verifications rely on MX records, which could point anywhere.
Quite right, but that's not my point.
My point is that legit mailservers have substantial incentive to
use something reasonable for HELO. Random junk for HELO _will_ cause
e-mail delivery problems to various servers that require one or
more of the "non-required" HELO tests.
For instance, there are servers out there that only accept mail if
HELO resolves to a server with port 25 open AND accepts mail to the
MFROM address.
That's not kosher, but it's not that uncommon (esp in Europe)
They won't be getting mail from us then. I've never had a complaint about
this, though.
If they can get away with all those hoops, then I can require that the
HELO at least resolve.
Yep. No reason not to do that.
Bottom line - I do not hesitate to require reasonable HELO values,
because unreasonable ones from legit servers are so very rare.
Fair enough.
-dgl-
-------------------------------------------
Sender Policy Framework: http://www.openspf.org [http://www.openspf.org]
Modify Your Subscription: http://www.listbox.com/member/
[http://www.listbox.com/member/]
Archives: https://www.listbox.com/member/archive/735/=now
RSS Feed: https://www.listbox.com/member/archive/rss/735/
Powered by Listbox: http://www.listbox.com
--
Ian Eiloart
IT Services, University of Sussex
01273-873148 x3148
For new support requests, see http://www.sussex.ac.uk/its/help/
-------------------------------------------
Sender Policy Framework: http://www.openspf.org [http://www.openspf.org]
Modify Your Subscription: http://www.listbox.com/member/
[http://www.listbox.com/member/]
Archives: https://www.listbox.com/member/archive/735/=now
RSS Feed: https://www.listbox.com/member/archive/rss/735/
Powered by Listbox: http://www.listbox.com