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Exchange 2010 Outgoing email broken after change of external IP address

Posted on 2013-01-08
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Last Modified: 2013-01-10
My Exchange server has stopped sending emails since my internet connection was changed and the external static IP address changed.  Before the change my server was sending emails through my ISP's smarthost and even though my internet connection has changed I'm still with the same ISP so I kept the smarthost as it was but immediately I started getting bouncebacks saying there was a delay delivering my emails.  These errors kept coming through throughout the day so I contacted the ISP who said they would create a reverse DNS record for my domain pointing to the new IP address so I deleted the SMTP smarthost in SBS console and told the server to send emails using DNS. This was done 6 hours ago and I still can't send emails so I ran the Remote Connectivity Analyzer for outgoing SMTP mail on my server which failed on the step "Attempting reverse DNS lookup for IP address: " then it gives my OLD external IP address.  I've run the fix my network wizard and the Connect to Internet wizard, other than that I can't seem to find where I'm supposed to let Exchange know that my external IP address has changed, is this likely to be the problem?

Thanks

Adam
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Question by:amlydiate
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11 Comments
 
LVL 5

Expert Comment

by:basil2912
ID: 38756858
Hello,

If the send connector has no special settings (except the smarthost) there shouldn'n be any problems.

Exchange sends mails using DNS and port 25 for SMTP.

Usually smarthost is accepting port 25 connections and is sending the mails further on the Internet.

My best guess - even I really understand is not a pleasure - to wait until ISP settles the smarthost issues (I really think the smarthost accepts connections on port 25 from certain IP addresses only).

You can investigate a bit on your side doing telnet [smarthost] 25 and see what is happening.

The error you get in the RCA shows clearly that the external DNS simply didn't update. (up to 72 hours unfortunately), although reverse DNS is used only for mail spoofing/ID checks - should be filtered on the receiving side not when sending.

What exact error do you have in SMTP logs? Usually they should show enough info to have a good idea where the problem might be.
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Author Comment

by:amlydiate
ID: 38756867
I've just checked MXToolbox, apparently the reverse DNS banner check for remote.mydomain.co.uk resolves correctly.  This is the subdomain which I use for my external FQDN of the exchange server, and the SMTP Reverse Banner check says my new IP address resolves to mail.mydomain.co.uk successfully, however my domains MX records point to mail.mydomain.co.uk (and always has done) but the SMTP reverse dns resolution on mail.mydomain.co.uk just times out.

Hope that helps

Thanks

Adam
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LVL 5

Assisted Solution

by:basil2912
basil2912 earned 167 total points
ID: 38756957
Hi,

Check this article http://ezinearticles.com/?Configure-Exchange-E-Mail-Server-Reverse-DNS-and-MX-Records-Correctly&id=3844191 - and see if the FQDN is set correctly on Exchange side.

Does the ISP require the use of the smarthost when sending e-mail? Is port 25 blocked?

Still looks ISP config problem to me...
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LVL 52

Assisted Solution

by:Manpreet SIngh Khatra
Manpreet SIngh Khatra earned 333 total points
ID: 38758765
Hope you have the MX and Ptr record corrected

For email flow check for (Inbound-Outbound email)
www.exrca.com

- Rancy
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Author Comment

by:amlydiate
ID: 38758812
Just tried the outgoing SMTP test on exrca.com and got the following results:


Performing Outbound SMTP Test


The outbound SMTP test was successful.

 
Test Steps

Attempting reverse DNS lookup for IP address MYIPADDRESS.

ExRCA successfully resolved IP address MYIPADDRESS via reverse DNS lookup.

Additional Details

ExRCA resolved IP address MYIPADDRESS to host mail.MYDOMAIN.co.uk.

 
Performing Real-Time Black Hole List (RBL) Test

Your IP address wasn't found on any of the block lists selected.

Test Steps

Performing Sender ID validation.

Sender ID validation was performed successfully.

Test Steps

Attempting to find the SPF record using a DNS TEXT record query.

ExRCA wasn't able to find the SPF record.

Additional Details

No records were found.
 
Does this suggest the problem is with the server itself rather than with domain/ISP?
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Author Comment

by:amlydiate
ID: 38758845
Just as an aside.  The reverse DNS record was set up as mail.mydomain.co.uk and pointed to my IP address, however the FQDN setup in the send connector in Exchange is remote.mydomain.co.uk  I tried changing that to mail.mydoain.co.uk but that still didn't work and I got errors in the log because mail.mydomain.com is not mentioned in my SSL certificate so I changed it back to remote.mydomain.com  From what I can see the send test in ExRCA seems to say everything is fine but I've got 20 messages stuck in the queue including a poison message whatever that is.

Really getting desperate now if anyone can please help!

Thanks

Adam
0
 

Author Comment

by:amlydiate
ID: 38758866
Interesting.  Just gone into the queue in Exchange and tried to delete the Poison Message and I get back a very long error message which I can't seem to copy and paste so will give you the jist of it below:

Exchange can't connect to the Microsoft Exchange Transport service on computer "MYSERVERNAME" Verify the service is started (just checked and it WAS started but restarted it anyway and that seemed to restart o.k.) It was running the command 'get-queue -ResultSize '1000' -ReturnPageInfo4true -SortOrder'+NextHopDomain' -server 'myservername'-SearchForward e.tc. e.t.c.

Does this shed any light?
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Expert Comment

by:Manpreet SIngh Khatra
ID: 38762858
I would suggest you rebuild or stop the Transport service and move the DB file for transport

- Rancy
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Author Comment

by:amlydiate
ID: 38762900
I've set up sending through a smarthost and it's all started working and the queue has emptied. Very frustrating as I was hoping to avoid using the smarthost...
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LVL 52

Accepted Solution

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Manpreet SIngh Khatra earned 333 total points
ID: 38763012
Thats strange not sure how Smarthost helps but maybe if its that way then some DNS issues for that Domain i assume

- Rancy
0
 

Author Closing Comment

by:amlydiate
ID: 38763033
Am splitting the points on this one as you all helped me with diagnosing the issue.  I'm going to leave the smarthost in place as it's just simpler tht way and at least outgoing mail is working now.  Thanks for your help guys
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