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Exchange 5.4.6 problem

Hello

My company is using some external marketing company to do bulk email.
Let's say our domain is example.com. We have an mx record mail.example.com.
We were asked to setup A, MX and TXT records for news.example.com so they could
spam people from address news@news.example.com.

Everything works fine, except for sending test email to our users with email addresses @example.com.

I asked them if they have any logs and they said that they are getting this:

'Looks like we're getting a "5.4.6 (routing loop detected) / routing-errors" error message back on the deliveries sent to the example.co.uk contacts.  

Please let me know if you have any further questions in the meantime.
'

I'm not sure what is going on, I don't even know if the emails are reaching our server at all (exchange 2007), I don't see anything in message tracking. I suspect a DNS problem but I maybe completely wrong.
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tp-it-team
Asked:
tp-it-team
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1 Solution
 
guswebbCommented:
It sounds like you have nominated their mail server as an authoritative receiving mail server for the domain via an MX record. When they send email, it is attempting to send the email externally but the MX record is pointing the SMTP connection back to itself and not to your server where the recipients are hosted. Double check the MX record settings and post back.
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guswebbCommented:
What you should have done is created an SPF record designating their mail server as authoritative to 'send' emails for your domain. Unless you want them to also receive emails for your domain, which is what has caused the loopback, you should not create an MX record for their server/IP.
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tp-it-teamAuthor Commented:
is it really all whats needed ? and SPF record in order for them to send email on our behalf?
Can you explain it to me or point me to a good article ?

They asked us to do this:

news.example.com.       A   their IP
news.example.com.        MX   10   incoming.one of their domains.com.
news.example.com.       TXT  "v=spf1 include:their domain.com -all"
news.example.com.       TXT  "spf2.0/pra mx include:one of their domains.com -all"

after what they requested, news.example.com resolves to their IP.

here is the MX LOOKUP result for my domain example.com
5       mail.example.com       our IP
5       news.example.com       their IP
10       relay.net                         here we will get emails queued if our server is down.

They actually asked for the weight to be 10 but I think it doesn't matter and still would be wrong.
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guswebbCommented:
There's your problem. The MX is pointing back to their server but it's not configured to receive email for your domain and is essentially a loopback.

For SPF record creation follow this link...

https://www.microsoft.com/mscorp/safety/content/technologies/senderid/wizard/

This is what I use to generate our SPF records. It looks like you may have already taken care of this in which case deletion of the MX record for their IP and pointing at your IP instead is all that is required.
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