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Troubleshooting incoming mail flow (or the lack thereof)

Usually you’ll get alerted to this issue with a call saying that users have not gotten any new email for a while. They will still be connected to Exchange in outlook, you can still log on to the OWA and, when looking at your hub servers, you can see that the all services are up and running (Note that it is possible the transport service could be stopped…).

A number of reasons can exist as to why you are not getting any mail flow:

· Your recipient polies are not configured correctly

· The receive connector is configured incorrectly

· The mx record no longer exists

· The mail server is not reachable from the internet

· You ran out of space on your queue database drives

Let us look at each of these possible issues individually…

Testing mail flow

Before we actually go ahead and look at each of the items I would recommend, if possible, to test mail flow by running telnet and using the ehlo commands to connect to the server from both external and internal servers. That way you can narrow down where the issue is located.

Recipient policies

The recipient policies are responsible for “stamping” your users with the correct SMTP (email) address. If your users are not “stamped” with the correct address you will not receive email. Very simple yet oh so annoying… This will most likely be a problem you run in to at the setup of a new domain. Checking if the correct recipient policy is set up is quite simple and resolving it even simpler.

For Exchange 2003:

1. Open up the Exchange system manager

2. Expand down to recipients, recipient policy.

3. Select the recipient policy and check that you have the correct domain(s) listed there

For Exchange 2007/2010:

1. Open up the Exchange management console (EMC)

2. Expand the organization configuration

3. On the Hub Transport item, select the email address policy.

4. Check that the policies have the correct domains listed.

It is important to note that you need to have the correct domain listed in the accepted domains tab under hub transport before a correct email address policy can be created.

Receive connector

Exchange needs a receive connector to allow mail servers to connect to your mail server and actually deliver mail.

For Exchange 2003:

1. Open up the Exchange system manager

2. Expand down administrative groups, first administrative group, routing groups, first routing group and select the connectors container

3. You should see the SMTP connector here, if not you will have to create a new one.

4. Take the properties of this connector and check them for accuracy.

For Exchange 2007/2010:

1. Open up the Exchange management console.

2. Expand down to server configuration, Hub transport

3. Select one server and check it has two receive connectors

4. On the default receive connector, right click and select properties

5. Make sure that on the security groups tab the “anonymous” entry is checked.

6. Check that the network tab is configured correctly.

7. Rinse and repeat for all servers listed in the hub transport tab.

MX records

The mx records are a part of the DNS infrastructure and let other mail servers know what IP to deliver the mail for your domain on. You can do a lookup for these records by using nslookup.

1. Open a new command (DOS) prompt
2. Type in nslookup
3. Set type=mx
4. Enter your domain name, e.g. toasterlabs.com
5. Make sure it returns the correct IP address for your domain.

There are a lot of things you can do with MX records. For more information please check:
http://en.wikipedia.org/wiki/MX_record

The mail server is not reachable from the internet

This could happen if a new firewall is installed but the rules and port forwarding are not configured correctly. If you want to test if the server is reachable from the internet try to use telnet to connect to the public ip address on port 25

telnet> o 132.157.125.23 25

Note that a default Exchange header response to this looks as follows:

220 hostname.domain.com Microsoft ESMTP MAIL Service, Version: 5.0.2195.1600 ready at Thu, 30 Nov 2012 18:09:43 -0600

If it does not look like this you are not connected to an Exchange server!

The mail queue

Exchange uses a number of queues to store the incoming mails before they get either sent on to other Exchange servers or delivers it locally. If the location of these queues are not changed they will be on the C:\ drive. As we all know, the C:\ drive has some strange gravitation field that causes it to fill up (unless you actually maintain that…). If you see it has less than 3GB available and you are not receiving email, you are faced with an automated protection mechanism that stops Exchange form accepting mail.

The mail queue

Exchange uses a number of queues to store the incoming mails before they get either sent on to other Exchange servers or delivers it locally. If the location of these queues are not changed they will be on the C:\ drive. As we all know, the C:\ drive has some strange gravitation field that causes it to fill up (unless you actually maintain that…). If you see it has less than 3GB available and you are not receiving email, you are faced with an automated protection mechanism that stops Exchange form accepting mail. This feature is called backpressure and is only present in the 2007 and 2010 versions of Exchange. Your C drive can, however, still fill up on an Exchange 2003 server Smile. In case backpressure strikes you should see the following events:

Event log entry for critically low available disk space
Event Type: Error
Event Source: MSExchangeTransport
Event Category: Resource Manager
Event ID: 15006
Description: The Microsoft Exchange Transport service is rejecting messages because available disk space is below the configured threshold. Administrative action may be required to free disk space for the service to continue operations.

Event log entry for critically low available memory
Event Type: Error
Event Source: MSExchangeTransport
Event Category: Resource Manager
Event ID: 15007
Description: The Microsoft Exchange Transport service is rejecting message submissions because the service continues to consume more memory than the configured threshold. This may require that this service be restarted to continue normal operation.

You have 2 possible ways to solve this:

1. Clean up your C drive

2. Move the transport queue location.

Personally I believe you should not leave the queues on the C drive as it is often overlooked, but then again, you should not allow the C drive to fill up anyway J.

To move the transport queues you should perform the following actions:

For Exchange 2003:

1. Open up the Exchange system manager

2. Expand administrative groups, first administrative group, servers, expand the server that is supposed to be receiving emails, expand protocols and lastly, expand SMTP.

3. Right click the SMTP virtual server and select stop.

4. Right click it again and select the properties.

5. Click messages and type in the new path for the Badmail directory and for the Queue directory.

6. Right click the SMTP virtual server and select start.

For Exchange 2007/2010:

1. Open up a notepad session as administrator (right click, run as administrator)

2. Open the following file through notepad: C:\Program Files\Microsoft\Exchange Server\Bin\EdgeTransport.exe.config

3. Find the following section <appSettings>

4. Change the <add key=”QueueDatabasePath” value=” “> /> to reflect the new path.

5. Save and close

6. Restart the transport service

7. Verify the new mail.que and trn.chk files have been created at the new path

8. Remove the mail and trn files at the old path.

This should cover most of the issues you can encounter with mail flow. It is important to remember that these are all solutions for “bigger” issues, aka all users have been affect. In case there are only a number of users that are experiencing no mails use the message tracking log in the Tools section of the EMC to find out if they were even sent any mail… They might just be unpopular J.


Feedback

# re: Troubleshooting incoming mail flow (or the lack thereof)

Gravatar I have found this article very useful though I am currently not very conversant with Exchange server 1/25/2013 3:09 PM | William Simbota

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