We are somewhat new to Proofpoint and an issue started last week that I can't figure out how to address. One of our users sends emails back and forth with somebody he does business with. Starting last week, email exchanges between the two sides are getting blocked as spam. I was able to fix inbound emails with the whitelist but I haven't been able to figure out how to address outbound emails from our side that are getting quarantined as spam.
How do you figure out why outbound emails are being blocked and then fix the issue? Thanks in advance.