Issue: We run issue with very strange mail routing. We are still in mixed mode with Exchange 2003 and Exchange 2010. One of users reported email delay happened to a specific DL.
Troubleshooting Steps:
After login to one of the mailboxes who received the email and found out very interesting routing behavior from the message headers:
Message was sent from an internal 3rd application, via port 25's PMTA. The message reached Exchange 2010 hub first, then forwarded to Legacy Exchange 2003 Connectors, then sent back to the Exchange 2010 Hub and back to users' mailbox on Exchange 2010.
The delay happened with some disk issue on one of legacy Exchange 2003 connector servers. First though could be due to the DL that has not be upgraded to Exchange 2010. Spent some time to upgrade all DLs at our Domains that all mailboxes have been upgraded to 2010 for a while. Working with scripts to remove space from alias, incorrect characters from DL alias such as "@", "(" or ")", BTW, here is the cmdlet I used to remove space, @, (, or ):
Get-DistributionGroup -ResultSize unlimited | foreach {$_.alias = $_.alias -replace '\s|,|\.'; $_} | Set-DistributionGroup
for removing space from alias or
Get-DistributionGroup -ResultSize unlimited | foreach {$_.alias = $_.alias -replace '\s|,|\.' -replace '\(|,|\.' -replace '\)|,|\.' -replace '\@|,|\.'; $_} | Set-DistributionGroup
Then run force upgrade of the DLs:
Get-DistributionGroup –ResultSize Unlimited | Set-DistributionGroup –ForceUpgrade
After that, you may still get some issue with some of DLs that you may have to manually upgrade.
All of DLs have been upgraded and the issue still existing.
After digging, and found out one of the Legacy Exchange 2003 Connector servers were running out of space. fixed the issue, reboot all Ex2003 connector servers and Exchange 2010 hub servers. Delay issue has been resolved, however, the strange email routing issue still existing.
Get-DistributionGroup |FL printed output to file and focused on print out of the DL we had the issue.
Finally I found the settings of the DL was specified with the legacy Exchange 2003 server that we had issue as expansion server. After removed the expansion server, The strange routing issue has been resolved.
Here is the cmdlet I used to change all possible DLs that may have such settings:
Get-DistributionGroup –ResultSize Unlimited | Set-DistributionGroup -ExpansionServer $Null
Keyword: DistributionGroup upgrade, Exchange 2003 connector, Routing issue, Expansion Server of DL.
