Some mail from dragonfly.users being rejected

[Matthew Dillon]

:Hi.
:
:I subscribed to the dragonfly.users mailing list yesterday.  I received
:the confirmation messages and I have received both postings since them
:from Justin C. Sherrill.  However, the two replies to him and
:3 additional postings have been rejected from my mail server because
:crater is rejecting the sender verify connection.  Here is my mail log
:entry on one of the rejected ones.
:
:2008-01-28 11:41:08 H=crater.dragonflybsd.org [216.240.41.25] sender verify defer for <users-errors at crater.dragonflybsd.org>: could not connect to crater.dragonflybsd.org [216.240.41.25]: Connection refused
:2008-01-28 11:41:08 H=crater.dragonflybsd.org [216.240.41.25] F=<users-errors at crater.dragonflybsd.org> temporarily rejected RCPT <vince.dragonfly at hightek.org>: Could not complete sender verify callout
:
:Any idea why crater rejects some sender verify connections and not
:others?
:
:Good thing we run our own virtual dedicated server and have root access
:to our mail logs, or I would not have been able to determine why some of
:the list mail is not getting through.
:
:I discovered it when I received a reply from Justin to Simon but had not
:received the posting from Simon.  I checked the list via the nntp server
:and discovered the 5 other postings I have not received.

    Hmm.  We're just running normal sendmail here.  But if the mailing
    list has several addresses that run through your server and your
    server is trying to do a backchannel for each one in parallel, you
    could be hitting up against crater's connection limit.

    It's isn't really legal to reject a message outright if you can't
    make a reverse connection.  You have to reject it with a temporary
    error code so it gets retried later.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>