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SBS 2003 Outgoing SMTP non-NAT (block of IP) reverse DNS problem

Working on an installation with a non NAT ISP connection (block of 10 IP's)

xx.xxx.xxx.217 is the main IP address
xx.xxx.xxx.218 is the mail gateway

Domain xxxxxx.org.uk is hosted remotey and resolves to host IP address OK

MX record for mail.xxxxx.org.uk points to xx.xxx.xxx.218 for the incoming mail server - receives mail OK

When email is sent out however it sends through xx.xxx.xxx.217 the main IP address
If the receiving domain uses revers DNS the IP address does not resolve to the domain / mail server and fails to send

My initial thoughts are to setup two MX records - "outmail" and the other "inmail"
inmail will point to xx.xxx.xxx.218 - mail gateway
oumail will point to xx.xxx.xxx.217 - main IP address

Then change the SBS virtual server properties with FQDN and Smart Host of outmail.xxxxxx.org.uk

Would this work or is there a simpler / better way of resolving the ougoing mail and reverse DNS resolution problem ?

Thank you for reading my post and considering your reply.
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NiSiWi
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NiSiWi
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1 Solution
 
vico1CIOCommented:
That would work with no problem.
However you could setup the 2 IP's as in and out you just have to route your SMTP port.
That will give some kind of redundancy just setup the 2 IP's With priority 10, 9 you got the point.
vico1
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heathcote123Commented:
I think just getting your ISP to configure a reverse dns entry for both IP's should work without any hassle.

The reverse DNS doesnt even have to match to your email domain, there just has to be one there.

Go to dnsstuff.com and check out whether you have one or not.

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NiSiWiAuthor Commented:
This is now very confusing

I have created two MX records - one for inmail and the other for outmail and both point at IP address .217 and .218.
When I run the dnsreport everything seems to check out OK, however mail is still being rejected by a specific domain as below.

      info@xxxxxxxx.com on 28/3/2006 21:47
            There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <xxxx.org.uk #5.5.0 smtp;550-Verification failed for <xxxxxxx@xxxxx.org.uk>>

Any ideas ?
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heathcote123Commented:
mx records are not the same as reverse dns - do both have revers dns entries?
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NiSiWiAuthor Commented:
turns out that I needed to turn off the email for the hosting account and everything started working OK
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