A few questions before I buy/trial SpamSieve

Pardon these very basic questions. I am trying to rid myself of epidemic spam coming through my verizon.net accounts by forwarding all my email to my IMAP iCloud email account. The ultimate goal is to close down all of my POP accounts and only use IMAP. Will SpamSieve work on forwarded email? In other words, will it recognize when the original sender is spam, or will it let everything through because it comes from my Verizon account? I don’t want to waste a lot of time learning how to use a program that won’t work with my situation, or bother C-Command for a free trial if it’s a no-go from the get-go. Thanks in advance

SpamSieve will work normally if you are using the sort of forwarding where the message’s “From” field (in iCloud) is the same as the original message’s sender. (This is how server-level forwarding usually works, but I’m not sure how Verizon, specifically, does it.) If the “From” always appears as your Verizon address, SpamSieve can still work (if you follow these instructions) but would be less effective.