MS Exchange not sending email to external users

Posted on 2013-01-08
Last Modified: 2013-02-04
We have an Exchange Server in our site with Mailstore located locally for the users in this site. Then we have the primary exchange server in our other site with mailstore located there for their users. We have secured private WAN connection to have these two servers communicated. For going out (external emails - hotmail) we have Ironport at both sites to go out through our local internet gateway (different from secured private WAN connection)

Now I am having issue sending email to external users (e.g. hotmail)…
-      The users in our site can send email to other site.
-      The users in our site can receive email form other site and from external address (e.g. hotmail)
-      The users in our other site can also receive emails from this site.
-      However, if I send an email to external usres (e.g. hotmail), hotmail not receiving the email. However I am getting successfully delivered receipt.

What could be the issue?

Also does MS Exchange server keep its own routing table?

When there is a change in the newtork dos it take long time to re-calculate the route/path? if so why and what does it do?

Thanks for you help.
Question by:Mike
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Expert Comment

ID: 38756870

What version of Exchange are we talking about?

The routing is pretty different depending on the version.

IS there a CAS/HUB server in both sites?

Do you have enough ironport licenses?

Expert Comment

ID: 38757061
Check you send connectors
LVL 52

Expert Comment

by:Manpreet SIngh Khatra
ID: 38758777
What could be the issue? - If everything else is working its simple Issue is at Recipient end HOTMAIL

Also does MS Exchange server keep its own routing table? - Some firewalls do not Exchange

When there is a change in the newtork dos it take long time to re-calculate the route/path? if so why and what does it do? - I guess your speaking about Tracert

- Rancy
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Author Comment

ID: 38758815
- The issue is not just hotmail, any external address (hotmail/yahoo/ any other domains)
- Yes we do have enough IronPort licenses.
- It is MS Exchange server 2007 and both site have Hub Transport, Client Access, Mailbox version 8.2 (Build 176.2)

Author Comment

ID: 38763786
Temporary we have are forwading the outbound emails also thorugh the WAN to the IronPort on other side, until we fix this problem. It now seems like some routing issue but it is not clear where it is breaking. Will need do a full scan on this. Thanks for your response. I will keep this open, if you have any suggestion please do let me know.  When I got it fixed, I will update too. Thanks.
LVL 52

Accepted Solution

Manpreet SIngh Khatra earned 150 total points
ID: 38764078
If you have multiple routing servers please check if they arent listed on some RBL and also Inbound\Outbound email flow

Inbound\Outbound email flow -
RBL check -

- Rancy

Assisted Solution

basil2912 earned 150 total points
ID: 38766242
To do some t-shooting you need to:
Enable verbose logging on the send connector;
Reproduce the issue;
Check logs to see the precise error code(you'll find them at \TransportRoles\Logs\ProtocolLog\SmtpSend ).

Follow-up t-shooting based on the error that you get.

Author Comment

ID: 38784735
Thanks Rancy and basil2912. I will check out these t-shooting options.

Currently we have EXCH > IronPort > CP FW > ASA > ISP Router > Public Internet.
I am working on getting rid of CP FW and connect IP directly to ASA to see if that would help.

Author Closing Comment

ID: 38852312
I decided to simplyfy our network topology and then try work on this. As current network is very complex and I cnanot trace things easily. If I find an answer I will come back and post it here. Thanks for you help.

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