Can't send message due to virus?

[#1]

I get the following error message from outlook when trying to send a particular message
552 7SMo1p0051eJSnl01SMp7L message rejected due to spam or virus. If you believe this is in error please login to your portal or contact your ISP support team
It is from her PN mailbox and I can't send it back to her or even send it to myself. It has two word docs attached nethier of which show anything on a scan.
Any clues?
Thanks

[#2]

Often a phrase in an email can trigger a "false positive" email rejection. The names of the documents could also trigger a false positive
Try sending each of the email attachments on their own email with no other text and a different subject line. 

[#3]

That sting of characters is a spam fingerprint used by our anti-spam vendor (Cloudmark). It's normally indicative of a problem with the content of an email. Typically, this tends to be mention of an email address or domain that Cloudmark doesn't like. This could be one of the addresses you're trying to send to, an address you're trying to send from or mention of a website address or email in the body or signature of the message.
If you raise a support ticket, explaining what's happening and including a copy of the fingerprint string, then we should be able to advise further.