'Collateral spam' is quite simply forged mail. It did not originate in the Institution that it appears to come from, as can be seen by the full headers.
You have been asked to look at this page because you are the recipient of Collateral spam from a forged Cambridge address. This might be an address
@hermes.cam.ac.uk. Cambridge is as much a victim of the spammers as the recipient.
The University of Cambridge is subject to the Acceptable Use Policy of our Internet Service Provider JANET, which forbids unsolicited bulk mailing and forgery of parts of mail messages; and we are working with JANET to identify the real origin of the mail you had.
Thank you for reporting the abuse. We are sorry you have been troubled.