I'm troubleshooting spam problems in Apple Mail (Mojave) on my computer. As part of that I've turned off spam filtering at the comcast server level. Now I'm wondering whether messages marked as spam by comcast are picked up or sent to the Apple Mail client. If so, how are these messages marked as spam? Does comcast change the header before Apple Mail client gets it?
(If anyone understands how the server-to-client email protocols work, they are welcome to get as technical as they wish.)
With Comcast's spam filtering turned off, spam is delivered to the Inbox where it should be available to email clients. I know of no official documentation of their spam tagging, but here are my observations. They add a header that looks like this to all email:
"Z" is a single letter that I do not know the meaning of, and is somtimes absent. "ABCD" is always "0000" for all the examples I've seen. "E" is "1" if they think the message is spam, and "0" if not spam.