Thursday, June 5, 2014

Exchange 2010 - Troubleshooting 'Delivery is Delayed' auto-replies..

So sometimes you try to email a person and you get a response back saying that delivery of your email has been delayed but that the server will keep trying to X amount of time.  Don;t worry.. it happens to everyone from time to time.
The list of possible causes are numerous.. everything from RBLs, DNS issues to high latency on someones internet pipe.

Below are some things you can do to help figure out where the problem lies:

I always verify the message left my queue via the Queue Viewer
Next would be checking the Message Tracking Logs, that can be handled a number of ways.  You could check it via /ECP (Exchange Control Panel) or via powershell (my favorite).  Try out the following commands:

Get-MessageTrackingLog -ResultSize "Unlimited" -Recipients "[recipient's address]"
Get-MessageTrackingLog -ResultSize "Unlimited" -Sender "[sender's address]"
Get-MessageTrackingLog -ResultSize "Unlimited" -Start "[date/time]" -End "[date/time]"


There are tons of variances to that cmdlet, you can even pipe the output to a .txt or .csv if so desired.  Which is very helpful when sifting through hundreds of lines of log.

Next is DNS.. sometimes a delay can be caused by a DNS resolution issue.  Verify your mail server can successfully ping and nslookup the target of their MX record.

Speaking of MX records.. another good tip is to verify that you nor them are listed on any RBLs.  I prefer MXToolbox myself, check their Blacklist tab and enter their domain name or SMTP ip address if you know it.  While you are there be sure to sign up for their free RBL monitor.  Once a month you get an email showing the RBL status of a single domain.  I've been using their service for over 4 years now, it's nice to know where your domain stands with regards to the MANY RBLs out in the wild.

Lastly verify all is good with your server at https://www.testexchangeconnectivity.com/

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