FAQ / Server Products

When I push email to Exchange via IMAP I get the error "BAD Command Argument Error. 11" or "NO Maximum size of appendable message has been exceeded" in newer versions!
This obscure but typically Microsoft error relates to the message size limits set on the IMAP server in Exchange. To change the limits you need to not only increase all your message size limits and account quotas within Exchange but also edit the IMAP configuration file within Exchange.

Exchange 2007/2010

To do this open the file:
c:/ Program Files / Microsoft / Exchange Server / V14 / Client Access / PopImap / Microsoft.Exchange.Imap4.exe.config

And add or set the following parameters towards the end of the file in the section:










Exchange 2013

To do this open the file:
c:/ Program Files / Microsoft / Exchange Server / V15 / Client Access / PopImap / Microsoft.Exchange.Imap4.exe.config

And add or set the following parameters towards the end of the file in the section:









Office 365/Exchange 2016

Office 365 supports send/receive max message sizes of up to 150MB
but you need to make changes in your tenant(s) to support it.

The following PowerShell command will increase the message sizes that
can be sent/received.

Set-mailbox -Identity $UPN -MaxReceiveSize 150mb -MaxSendSize 150mb

e.g.

Set-mailbox -Identity "migrationaccount@testtenant.onmicrosoft.com" -MaxReceiveSize 150mb -MaxSendSize 150mb

If we're transferring data between Office 365 tenants so we set these
values on the migration acounts in the source and target tenants.

There are also the following guides: