Unable to send message;Reason:554 5.2.3 Mail Policy violation : Mail Size exceeds limit

Unable to send message;Reason:554 5.2.3 Mail Policy violation : Mail Size exceeds limit

I keep getting this error.

Unable to send message;Reason:554 5.2.3 Mail Policy violation : Mail Size exceeds limit

And the mail size is smaller than 25Mb

-Roger