Email rejected despite no size limitation imposed

10.10.3, Server 4.1

Two different people tried to send me a 7.8mb PDF. Here's the rejection message:

Delivery to the following recipient failed permanently:

info@XXX.com

Technical details of permanent failure:

Google tried to deliver your message, but it was rejected by the server for the recipient domainXXX.com by mail.XXX.com. [XX.XX.XX.XX].

The error that the other server returned was:

552 5.3.4 Message size exceeds fixed limit

I looked at the settings for the user, no limit imposed. I looked at the main mail settings, no limits imposed. Am I missing something somewhere? Is there a default limit set within some configuration file? Is there a way to override that without getting into the file itself?

Thanks in advance!