ShadowRedundancy queue large email issue

Question

issue description:

Exchange 2013 on premium enviroment, I notice there are large email (about 200 every day) in ShadowRedundancy queue on several Exchange Mailbox, could you help the following question, thanks:

1. Will large number emails in ShadowRedundancy cause email delivery issue? delay deliver or other issue?
2. Is it a normal behavior? what is the reason for this kind of issue and how to resolve?

Answer 1

Hi,

Welcome to the Microsoft Q&A forum.

Based on your description, I'd like to know if all of these emails were successfully completed for delivery. If the emails are all accepted and sent normally, we suggest you to observe for some more time. For your question, this phenomenon may indeed mean that some emails failed to be delivered, you can use Event Viewer to check if there are any errors. Here is a similar issue for your reference:https://community.spiceworks.com/t/exchange-2013-mails-stuck-in-shadow-redundancy-with-status-ready-expired/768362

It is not typical to have a consistently large number of emails in the ShadowRedundancy queue.There are a number of reasons why this might happen：

• Network issues: Latency or connection problems between Exchange servers can prevent acknowledgments from being received in a timely manner.
• Server issues: Performance problems on either the primary or shadow server can cause delays in processing and acknowledging messages.
• Configuration issues: Misconfigurations or insufficient resources allocated to the Exchange servers can also contribute.

You can use Exchange Management Shell (EMS) commands to get more insights:

Check queues:

 Get-Queue | where {$_.DeliveryType -eq "ShadowRedundancy"} 

Detailed queue status:

 Get-Queue -Identity <QueueIdentity> | Format-List 

Transport server health:

Get-ServerHealth -Identity <ServerName> -HealthSet Transport 

By examining these aspects, you should be able to identify and address the cause of the high number of emails in the ShadowRedundancy queue.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.