Has anyone seen this error

I have a user getting this error when trying to send an excel spreadsheet:

552 MS-Office file containing VBA macros found inside of the email

He can send the attachment to me which means that the proble is not coming from within their network.

I have tested this on our other network and through a gmail account and got the same response.

He claims he was able to send through a web based email but I’m not sure about that.

Thanks for any help on this!