Azure Hybrid & Cloud Migration Blog

Author: Zahir Hussain Shah, MVP Exchange

Changing Exchange Attachment size is pretty straight forward, and can easily be changed, as per your companys e-mail policy, but at times it becomes frustrating after changing all the required settings, but still Outlook doesnt allow you to attach new larger attachments as per your new settings.

So what is the problem, what is still pending which is stopping Outlook from accepting larger attachments?

Recently, I had a same situation, where after changing the following settings and verifying still, Outlook didnt accept the large attachments:

For seeing the step by step method of configuring the below, see my this past blog post.

Changing and Verifying Hub Transport, Global Settings for Max Sending, and Max Receiving limits.

Changing and Verifying Hub Transport, Send Connector Max Sending Size.

Changing and Verifying Hub Transport, Receive Connector Max Receiving Size for both Default-Server, and Default-Client connectors.

Verifying user has required message delivery restriction, by default users are allowed to send and receive unlimited size of message.

AD Site Link default Max Size, also checked found that it is also unlimited (by default)

Problem:
So we verified everything, why still we are seeing problems for Outlook?

Cause:
The problem is that some of the Exchange messaging organizations are transitioned and were migrated from legacy Exchange version (2003/2007), and therefore on each Routing Group Connector, there is a maximum size limit of the message to travel, and this is what which stops the Outlook to accept the larger attachments more than the default of 10 MB.

Solution:

Run the below CMDLet to find all the Routing Group Connectors, and change their MaxMessageSize limit to the same as what you are trying to set for your new e-mail attachment size limit.

Cheers,