How to adjust message size limits for the Mail service for each account?

I have learned how to adjust message size limit for the Mail service from this article:
OS X Server: Adjusting message size limits for the Mail service

However, we we many accounts in the server and we need to adjust different message size limit for different accounts.

Does anyone know how to modifiy the following command to set up different message size limit for different accounts?

sudo serveradmin settings mail:postfix:message_size_limit = number

Thanks,

Clement