How Do I Change Message Size Limits in Exchange 2007?
[Today's post comes to us courtesy of Shawn Sullivan]
Size limits for email messages are controlled in a variety of places in Exchange 2007. Settings are placed globally at the transport level, on each individual send or receive connector, and at each individual mailbox. Your business needs should determine if you need to change these settings and at which location(s). In order to accomplish this successfully, you must know that more restrictive settings override less restrictive settings as you flow up the chain from individual mailbox settings to SMTP connectors and finally to global transport settings.
Global Transport Settings
Get-TransportConfig displays global transport settings for all Hub and Edge Transport servers in the Exchange Organization. By default, there is a 10MB size limit on send and receive. This will override all other less restrictive message size limit settings set elsewhere.
NOTE: Exchange 2007 considers message submission to the store driver as a “send” operation. Therefore, if you are attempting to receive an email message on an SBS 2008 server from the internet that is greater than the MaxSendSize of the global transport configuration, delivery will fail
Get-TransportConfig | ft MaxSendSize, MaxReceiveSize
Example:
Set-TransportConfig –MaxSendSize 20MB –MaxReceiveSize 20MB
Receive Connector Settings
Each receive connector is created with a default 10MB message size limit. A default install of SBS 2008 will contain a default receive connector (created during Exchange setup, do not remove this), an internet facing receive connector, and a receive connector for fax receipts and Sharepoint email notifications. The Windows SBS Internet Receive connector is the only one that you should ever need to adjust settings for. NOTE: If the global receive size is more restrictive, it will override this setting
Get-ReceiveConnector | ft name, MaxMessageSize
Example:
Set-ReceiveConnector “Windows SBS Internet Receive Servername” –MaxMessageSize 20MB
Send Connector Settings
Each send connector is created with a default 10MB message size limit. In SBS 2008, a single send connector is created for email destined for mail hosts outside of the site. If you need to adjust the size of messages flowing out of the SBS server, then you would change it here. **If the global send size is more restrictive, it will override this setting**
Get-SendConnector | ft name, MaxMessageSize
Example:
Set-SendConnector “Windows SBS Internet Send Servername” –MaxMessageSize 20MB
Mailbox Settings
Exchange 2007 does not govern message size limits at the mailbox level by default, as it relies on elements in the transport service for this. However, you can set size limits here if you want granular control without potentially affecting all senders and recipients. **More restrictive settings at the SMTP connector level will override here; more restrictive settings at the global level will override both**
Get-mailbox | ft Name, MaxSendSize, MaxReceiveSize
Example:
Set-Mailbox “test” –MaxSendSize 10MB –MaxReceiveSize 10MB
Errors and Causes
Trying to find exactly where a message size is being blocked can be somewhat tricky. Knowing where the settings are is important. However, identifying the different errors and NDRs that you are receiving and understanding where you should check first is just as important.
Scenario 1:
This NDR is generated by the sending server:
The following recipient(s) could not be reached:
test@contoso.com on 10/15/2008 3:54 PM
This message is larger than the current system limit or the recipient’s mailbox is full. Create a shorter message body or remove attachments and try sending it again.
<fourthcoffee.com #5.2.3 smtp;450 5.2.3 Msg Size greater than allowed by Remote Host>
- Check MaxReceiveSize on Global Transport settings
- Check MaxMessageSize on the Internet facing receive connector
Scenario 2:
This NDR is generated by the receiving server:
The following recipient(s) could not be reached
test@contoso.com on 10/15/2008 4:51 PM
This message is larger than the current system limit or the recipient’s mailbox is full. Create a shorter message body or remove attachments and try sending it again.
<contoso.com #5.2.3 smtp;550 5.2.3 RESOLVER.RST.SendSizeLimit; message too large for this sender>
- Check MaxSendSize on Global Transport settings
- Check MaxMessageSize of the send connector on Edge server (if you have deployed one).
- Check MaxReceiveSize on the user’s mailbox
Scenario 3:
A user in the organization has attached a file to an email and receives an error like this:
Or the user receives this NDR from the SBS server after a failed delivery:
Delivery has failed to these recipients or distribution lists:
administrator@fourthcoffee.com
This message exceeds the maximum message size allowed. Microsoft Exchange will not try to redeliver this message for you. Please make the message smaller -- by removing attachments, for example -- and try sending it again, or provide the following diagnostic text to your system administrator.
Diagnostic information for administrators:
Generating server: COUGAR.contoso.local
administrator@fourthcoffee.com
#550 5.2.3 RESOLVER.RST.SendSizeLimit; message too large for this sender ##
- Check MaxSendSize on Global Transport settings
- Check MaxMessageSize on the send connector
- Check MaxSendSize of the user’s mailbox
