A while back, I wrote a post on the issue with sending large attachment in Blackberry Work. Recently, my service desk brought to my attention the errors below when downloading large attachments also in Blackberry Work.

After confirming the size limit for sending attachment within Blackberry Work app configuration, I switched my focus to settings in my Microsoft Exchange environment.

The links below helped with my investigation and resolution to this issue.

• Message size limits
• Configure client-specific message size limits

Let’s start with the setting in the Exchange organization-wide message size limits.

In the Exchange admin center, first check the maximum receive message size under:

1. Click on mail flow -> receive connectors
2. Click on … above and select Organization transport settings
3. Review and modify the values as needed (default value is 10 MB)

Optionally, review and modify similar setting within the relevant receive connector(s):

1. Click on mail flow -> receive connectors
2. Select a connector and click on the pencil icon to edit
3. Under the general tab, modify the value as needed

The reason I suggest this is optional because the default value is already set at 35/36 MB depending on the specific connector.

Transport service on Mailbox servers

• 35 MB for the Default and Client Proxy Receive connectors

Front End Transport service on Client Access servers

• 36 MB for the Default Frontend and Outbound Proxy Frontend Receive connectors.
• 35 MB for the Client Frontend Receive connector.

Next, we will look at the client-specific message size limits. These values can be configured in web.config files on client access servers and mailbox servers.

Per Microsoft KB, the default value for maxAllowedContentLength is already set at 30 MB even though it’s not present in the web.config file.  We can confirm this by browsing to the below in IIS of the Exchange server (it’s the same for both Default Web Site and Exchange Back End):

Also per the same KB, we are to check and change the value of maxRequestLength and MaxDocumentDataSize in the web.config file to match what’s configured for maxAllowedContentLength (i.e. 30 MB).

“To change the maximum message size for ActiveSync clients, you need to change the value of maxRequestLength in the web.config file on Client Access servers and Mailbox servers, MaxDocumentDataSize in the web.config file on Mailbox servers, and maxAllowedContentLength in IIS Manager on Client Access servers and Mailbox servers.”

• <httpRuntime maxRequestLength=”30720” /> (values displayed in bytes)
• <add key=”MaxDocumentDataSize” value=”31457280“> (values displayed in kilobytes)

Keep the below in mind when modifying this value:

• Any customized per-server settings you make in Exchange XML application configuration files, for example, web.config files on Client Access servers or the EdgeTransport.exe.config file on Mailbox servers will be overwritten when you install an Exchange Cumulative Update (CU). Make sure that you save this information so you can easily re-configure your server after the install. You must re-configure these settings after you install an Exchange CU.

I hope this helps with your issue too!