Spam filtering odd behaviour

[mrbios]

After some advice from the hive mind of edugeek...

 

I've got one spam filtering rule for the whole school, the same settings apply to me as applies to the member of staff having an issue. The county council are trying to email a member of staff but every email ends up being filtered as spam by our spam filtering policy. If they CC me into the email, it comes through to me without any issue at all.

 

I've got gloucestershire.gov.uk (the county council) as an allowed domain in my spam filtering policy, so they shouldn't be getting filtered by it at all. There's nothing i can decipher within the message header to indicate an issue.

 

I'm at a loss as to why this is being blocked, the email literally contains text, no attachments, and one link to the gcc website... so there's no content it could be picking up on either.

 

Any ideas where i go from here to determine what's going on?