I just received a nasty e-mail from the CEO of our company the other day complaining about why I am blocking e-mails to his real estate agency. He received a bounce back saying it was blocked as spam by a barracuda spam filter.
I dont even have a barracuda spam filter. Like you said I control every e-mail system in the world.
Every time an e-mail does not get delivered properly for ANY reason its me and my systems fault. I would say about 1 out of every 10 times its something on our end. Usually its on their end but nobody wants to hear that. Just fix it.