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SBS 2008 Refusing Email From AOL & Yahoo

Posted on 2013-06-05
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Last Modified: 2013-06-07
Hi Experts

Ive got a clients SBS2008 server that seems to be refusing emails from both AOL and Yahoo  and we cant seem to see why. We have checked everything from the black hole router issue to recreating the SCL levels and adding the domains to the BypassedSendersDomains queue but I still cant get mail in. Hotmail is fine oddly enough. Ive checked the transport logs and the mail isnt even being rejected from what I can see.

Any help would be greatly appreciated.

Cheers Simon
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Question by:leehewson
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by:Kent Fichtner
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Do you have any sort of Spam filter (Exchange, 3rd party, Internet security suite, firewall)?  If you send the exact same message from Hotmail and AOL is it still blocked on AOL (This is checking to see if it is marking something as spam)?

Also can you send from internal to AOL?  Have you tried multiple internal email address for AOL?
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by:leehewson
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Hi

there isn't any spam filtering, this has been removed whilst we attempt to resolve the issue. Outbound emails aren't affected and can be sent to any domain, it just seems to be inbound from AOL and Yahoo. Oddly the emails aren't hitting the server from what I can see.
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by:PaciB
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Hi,

When you say you checked the transport log you mean you've enabled the logging on the receive connector and took a look at the log file in "\TransportRoles\ProtocolLogs\SMTPReceive\..." ???

If the mail does not hit your Exchange server it's no need to look for something wrong on it...

You should instead take a look at your MX records.


Have a good day.
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by:Kent Fichtner
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PaciB, good point, but I would think that if Hotmail can come through then it can't be the MX records.  It seems that an issue with those is an all or nothing problem.
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by:leehewson
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Thanks PaciB - looking in the wrong place..... d'oh.

I can see that im getting 451 4.7.0 Timeout waiting for client input from my Yahoo tests which seem to point to an issue with the router possibly?
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by:PaciB
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Amerilabkfichtner,
Almost all messaginf systems try to resolve a MX record at first, and then try to resolve a host name if the MX doesn't exists.
Has an example, if you send an e-mail to "johndoe@unknown-domain.net" all the SMTP servers will at first ask DNS for the MX record in the zone "unknown-domain.net" and if the MX record does not exist ALMOST all the SMTP servers will then ask DNS for the A record "unknown-domain" in the "net" DNS zone...

To be more clear, SMTP servers try first to find a MX record matching the SMTP domain suffix and if this MX does not exist they try to find a host that have this name.

If they find a host with the matching name they will send the e-mail to this host...
This behavior comes from the very first implementation of the SMTP protocol, at the time where MX records were not oftenly used.

That's why this case might be caused by a missing MX record. SMTP servers at AOL and Hotmail may only search for a MX and refuse to send to a host....

Have a good day.
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by:Kent Fichtner
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leehewson, didn't mean for a thread hijack but PaciB I appreciate the explanation.

take care
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PaciB earned 500 total points
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leehewson,

Ok so finally you've got traces of an incoming SMTP dialog.

Yes you're right. The most probable explanation is a packet dropping somewhere...
I don't think it's about IP routing because the TCP session has to be established before your serve can trace anything in the SMTP log and that prooves the IP routing is good between your server and AOL servers.
But may be a firewall somewhere drops packets due to an incorrect rule.

The problem for you is that this case may have nothing to do with your server and you might not be able to diagnose by yourself. It can take a long time to find the cause and, more than that, to find the good person to resolve this.

Good luck
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by:leehewson
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Thanks PaciB, ive checked the IP address of the yahoo server and it appears to be blacklisted so im wondering if the ISP is blocking the DNS look up.
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by:PaciB
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Hi again,

Blacklisted by your ISP ?
Do you mean that your ISP provides you some SMTP incoming relay server ?
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by:Hir0
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Sounds like you might be using a smart host?  Yahoo, AOL, Goddady etc. frequently get abused by spammers and end up on various blacklists.  This is an unfortunate side affect of these companies hosting free email on the same servers as their business customers.  Are you having problems with email from the yahoo domain or domains hosted by yahoo ( AOL?).

You may need to work with your ISP to unblock these emails
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by:leehewson
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OK

So Ive been to site and have replaced the router and all so far is working well. Emails for all domains are flooding in. Thanks for your input, if things change ill let yo know.

Cheers Si
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Author Closing Comment

by:leehewson
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Put me in the right direction.
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