How to get a more human-friendly quota bounce message

[Russell Jones]

I have Postfix 2.3.3 installed, and am using standard file system quotas 
for users. Whenever a user receives a message and the message cannot be 
delivered to them due to being over quota, the following bounce messages 
is sent back:

russell-example....@server2.example.com 
<mailto:russell-example....@server2.example.com> (expanded from 
russ...@example.com <mailto:russ...@example.com>): can't create user 
output file


How would one go about changing "can't create user output file" to being 
more friendly? Such as "Quota exceeded".

Thanks!