Problem receiving mail - sender verify callout

[AlanH]

I haven't received mail from the XRV.org.uk server for a while so I thought I'd check our mailserver logs. It looks like the XRV.org.uk server isn't responding to sender verify callouts so our server thinks it's a spammer. Maybe something needs a tweak?


2008-12-09 09:08:58 H=www.xrv.org.uk (xrvcolo.merula.net) [217.146.105.54] F=<daemon@xrvcolo.merula.net> temporarily rejected RCPT <####@########.com>: Could not complete sender verify callout
2008-12-09 09:08:58 H=www.xrv.org.uk (xrvcolo.merula.net) [217.146.105.54] sender verify defer for <daemon@xrvcolo.merula.net>: could not connect to xrvcolo.merula.net [217.146.105.54]: Connection refused

[Lumiya]

The merula servers have never responded to verify callouts... In fact even EXIM and a few other mail server softwares have stopped setting the callout option by default..

Jen and I had the same problem when she first joined..

If your mail sever has only just stopped receiving the emails then that's a good sign that you;ve had a recent config/mailserver upgrade which has set call-outs by default...

[AlanH]

The merula servers have never responded to verify callouts...

Interesting approach. What's the thinking behind that then?

We have had a server move and sender verification callouts are enabled as it drastically reduces levels of spam.

[Lumiya]

Callouts only verify that the server reverse DNS's, cool if you have a primary server domain but useless if your connection doesn't rDNS...

We found that a lot of servers do NOT rDNS and we were missing some very important emails... So we turned it off, as we had the usual IP blacklists set up combined with a properly configured Spam Assassin after turning off callout we only noticed a 1% increase in spam that got through the system..

Anyway it's a fact that Merula does not have a true rDNS for their mail servers which will effect people using the CALLOUT function.. Not sure if the new server will be any different but in the mean time if you want XRV emails then you;ll have to either disable callout or change your email address to another server that you can redirect from...

Sorry it's not much help

[AlanH]

Callouts only verify that the server reverse DNS's, cool if you have a primary server domain but useless if your connection doesn't rDNS...

Not quite - A sender verify callout actually contacts the MX server for the domain of the email address and requests verification that the email address exists.

The reverse DNS should always be set for the server IP that is sending out mail.

[Lumiya]

Verify does the email address check where callout does the rDNS, they're actually two seperate commands that though are used together. You can still use verify without callout..

[AlanH]

Verify does the email address check where callout does the rDNS, they're actually two seperate commands that though are used together. You can still use verify without callout..

Other way around.

[Lumiya]

LOL, my mistake...it has been a year or two since I left EXIM and went over to a win32 option and now eventually back to postfix

Either way the fact still stands that merula doesn't support call-outs...

It does though raise a thought that for the new server perhaps a change in the way VB uses the server...perhaps a SMTP setting for scripts instead of sendmail...

Dave or Cie..could this be possibly done using the new SMTP/POP that we've started using??

[AlanH]

If you do that (I assume you mean using an external SMTP server rather than send via the xrv.org.uk server) you'll need to ensure that the SMTP server you're using supports sender verification callouts.

Anyway, I've turned off Sender Verification Callouts and it's now spam o'clock here but at least I can get my xrv.org.uk mail

[Lumiya]

The thing is though that in 2 years only two people have ever complained about it, you're one, I'm the other one