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Can't send emails to some domains

Hi Experts,

I have a problem with sending outgoing emails from my exchange to some specific domains, usually domains like (.co.uk - .co.ae - .net.sa)

I have a SMTP Connector setup on the Frontend Exchange and configured to use DNS and with an address Space of (*). When i ticked the (Allow messages to be relayed to these domains) the messages gone out but i can't keep this because i don't want to put my mail server in the street :)

How can this problem be managed without configuring my mail server for open relay ??
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ashkaat
Asked:
ashkaat
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1 Solution
 
SembeeCommented:
I am surprised that the setting fixed the problem.

Can you do nslookups on any of the domains that you are having problems with?

For example... microsoft.com:

C:\>nslookup
Default Server:  server.domain.co.uk
Address:  192.168.1.1

> set type=mx
> microsoft.com
Server:  server.domain.co.uk
Address:  192.168.1.1

Non-authoritative answer:

microsoft.com   MX preference = 10, mail exchanger = mailc.microsoft.com
microsoft.com   MX preference = 10, mail exchanger = maila.microsoft.com
microsoft.com   MX preference = 10, mail exchanger = mailb.microsoft.com

maila.microsoft.com     internet address = 131.107.1.7
maila.microsoft.com     internet address = 131.107.1.6
mailb.microsoft.com     internet address = 131.107.3.123
mailb.microsoft.com     internet address = 205.248.102.77
mailc.microsoft.com     internet address = 205.248.102.78
mailc.microsoft.com     internet address = 205.248.102.79
>

When you have the MX server information, see if you can telnet to port 25 of the remote server.

For example (using the above information)
telnet maila.microsoft.com 25

Simon.
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ashkaatAuthor Commented:
Hi Sembee,

I'm also suprised about this, i can DNS to these domains and i get the responsible MX Record for them .. for example:

C:\>nslookup

> qatar.net.qa
Name:    qatar.net.qa
Address:  82.148.100.100

> set type=mx
> qatar.net.qa

qatar.net.qa    MX preference = 10, mail exchanger = mail.qatar.net.qa
qatar.net.qa    nameserver = ns2.qatar.net.qa
qatar.net.qa    nameserver = ns3.qatar.net.qa
qatar.net.qa    nameserver = ns1.qatar.net.qa
mail.qatar.net.qa       internet address = 82.148.100.100
ns1.qatar.net.qa        internet address = 212.77.192.10
ns2.qatar.net.qa        internet address = 212.77.192.13
ns3.qatar.net.qa        internet address = 212.77.192.15
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ashkaatAuthor Commented:
When i tried to send an email from my domain though Telnet to this domain, i get:
550 5.7.1 Unable to relay for aawqtr@qatar.net.qa

When i tried to Telnet "mail.qatar.net.qa" on 25, i get:

220 ****************************************************************
Connection to host lost.


The above lines is exactly like i recieve !!!???
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ashkaatAuthor Commented:
For another domain "sps.net.sa", when i tried to send from my side, i get:
550 5.7.1 Unable to relay for aaw@sps.net.sa

But when i tried to connect to "mail@sps.net.sa" i could connect and send my mail .. they are using ESMTP

Any Suggestions ??
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SembeeCommented:
The lines you are receiving from mail.qatar.net.qa means that they have a Cisco PIX with the fixup SMTP option enabled. That is well known for causing problems.

When you setup the SMTP Connector, is it set to use the frontend server ONLY as the bridgehead? No smart host has been configured?
You haven't attempted to configure a smarthost directly on any of the SMTP virtual servers?

The results you are seeing are odd, to say the least. It indicates that you can connect to the servers directly. Therefore the problem must be inside your Exchange configuration somewhere. I am wondering if you have looped back on yourself somewhere.

Simon.
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ashkaatAuthor Commented:
The configuration of the Connector is to use DSN to route and only My Frontend Server is used as local bridgehead. No Smart hosts are configured on any of the SMTP Virtual Servers.

I don't think i've looped back because other internet emails are going out with no problems.
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ashkaatAuthor Commented:
Are we run out of Suggestions Here ?
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SembeeCommented:
Check that your DNS, Reverse DNS and SMTP banner are correct.
http://www.amset.info/exchange/dnsconfig.asp

If that doesn't fix it, then you will have to presume that you are being blocked by the remote sites and route email through your ISPs SMTP Server.

Simon.
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ashkaatAuthor Commented:
Hi Sembee,

I've made sure that everything is configured well including the DNS and SMTP banner. I still have the problem, nad i don't think these domains are blocking us because they are our company partners !!!
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ashkaatAuthor Commented:
Now, the problem is occuring with Hotmail and Yahoo !
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SembeeCommented:
If the remote sites are using a third party blacklist they may not know that they are blocking you. It is one of the reasons why I don't use third party blacklists as you don't have any control over them.

If it is happening with Hotmail and Yahoo then you have no other choice but to use an SMTP Connector to route email through your ISP.

As you haven't supplied your domain name I cannot check whether you are on any DNS or IP blacklists.
There are tools on the internet that can do the checks for you - dnsstuff.com has some.

Simon.
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