Increase incoming message size limit

Hi,

We've just increased the message size limit using the EAC (Mailbox Features-->Message Size Restrictions) of a particular user to 15000 kb.

Now when I test from the external an email of 13mb, I got a bounce saying 

The error that the other server returned was: 552 5.3.4 Message size exceeds fixed limit

Is there anywhere else I should check for increasing message size limits? Or is it just taking some times? Or maybe a service I should restart?

(Forgot to mention, we are using Exhange 2013 Server.)

Thanks to all

Martin