OS X Server: Adjusting message size limits for the Mail service

The message size limit may be increased or disabled via use of the serveradmin command in Terminal.

In OS X Server (Mountain Lion) and OS X Server (Mavericks), the default Mail service configuration limits delivery of messages to 10 MB or less. Messages larger than 10 MB will be rejected by the Server.

To change the message size limit, execute the following command:

sudo serveradmin settings mail:postfix:message_size_limit = number

The number in the command above is equal to the desired message size limit in bytes. To calculate the correct value for the desired size limit, multiply the MB value by 1048576. For example, for a 20 MB limit, the calculation would be 20x1048576=20971520. The number in the above command would therefore be 20971520.

Note: Excessively small values will result in the loss of non-delivery notifications, when a bounce message size exceeds the local or remote MTA's message size limit.

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To disable the message size limit, execute the following command:

sudo serveradmin settings mail:postfix:message_size_limit_enabled = no

Note: The size limit can be reinstated by using the same command with a value of yes in place of no.

You can check the current message size limit value with this command:

sudo serveradmin settings mail:postfix:message_size_limit