On 6/5/2012 10:44 PM, Viktor Dukhovni wrote:
On Tue, Jun 05, 2012 at 09:46:16PM -0600, Curtis wrote:
However, I'm not sure I fully understand why this fixes the problem
for outbound email. On outbound email, Postfix is acting as the
client and therefore one might think that
smtpd_discard_ehlo_keyword_address_maps would not have any effect,
since this setting is supposed to suppress EHLO keywords in response
to a client.
Correct the Postfix SMTP server-specific setting has no effect on
Postfix SMTP client behaviour.
Does smtpd_discard_ehlo_keyword_address_maps also
ignore EHLO keyword responses it receives on outbound connections?
NO.
I'm guessing so, because unless something else changed, the solution
worked.
The observations are erroneous.
Actually it was my reference to smtpd_discard_ehlo_keyword_address_maps
that was erroneous. (Thanks Ralf for pointing out my error!) The
actual parameter name referenced in the solution that Wiestse provided
in the thread I referenced was smtp_discard_ehlo_keyword_address_maps
(no d).
The fix I implemented was actually
smtp_discard_ehlo_keyword_address_maps (no d) as well. When I went to
look up the parameter in the documentation to see why it worked, I got
my parameter names mixed up, which is why I was confused as to why the
solution worked. Now that I'm looking at the right parameter name in
the documentation, it is clear that
smtp_discard_ehlo_keyword_address_maps does the job for outbound
connections.
I don't get into the Postfix configs often enough, as I had forgotten
that there were several parameters that were so similarly named (which
is actually a good thing once you understand the naming scheme).
Does anyone have any
experience with just turning it off completely for all hosts? Which,
I suppose would be done like this:
I've never had to work-around remote PIPELINING issues at remote
sites and I ran a fairly busy MTA plant delivering ~2M messages
per day. Some people have reported a small number of sites for
which they needed work-arounds, but you should not be seeing
a lot of remote peers with the issue unless there is a problem
with a firewall at your site. Fix that.
Our mail servers are busy here too. I think you'll start to see some
issues as well, as Wietse clearly shows that there are some broken
servers out there:
http://www.mail-archive.com/postfix-users@postfix.org/msg44135.html
The one referenced in the above thread is a Lunarpages server, which is
where we first ran into the same problem, and now we've run into the
issue with a Bluehost server as well. Bluehost claims to host millions
of domains and I suppose Lunarpages isn't that far behind. I suspect
they each have several hundred mail servers between them that would all
need to be added to the exceptions list that Wietse recommended. I
think these hosts broke something in May as we've just started get
complaints of intermittent issues delivering to them.
So again, I'll ask if anyone out there has resorted to turning off
pipelining on outbound connections? ...
smtp_discard_ehlo_keywords = pipelining,silent-discard
(Again, this time without the d.) Aside from a little extra bandwidth,
would this cause outbound deliveries to go horrendously slower on a busy
mail server?
Thanks,
Curtis
