A true story:
One of the PR professionals that I work with frequently uses Verizon hosted email for work purposes.
I sent to the team a draft copy of my upcoming report, and put in the title the report's title: The Spam Index Report. Well, Elyse never got it. Then George sent her the message with a new subject and body, where 'spam' was used in the body. Didn't get that either.
Then, George sent her the report with a different subject and spam spelled with spaces: s p a m. That one worked.
Note to self:
when doing marketing of anti-spam activities be aware that some filters think anything with spam in the title or in the body makes it spammy.