Running SpamSieve (2.9.39) on always on home iMac (10.15.4) with 3 accounts Gmail, Work and iCloud. No account changes in years.
Turned off Gmail server side spam filter with the recommended “Never send to spam” filter in the manual long ago. Recently logged on to Gmail on the web (which I almost never do) and there were 100s of spam messages in the Gmail Spam Folder (and 1 or 2 good messages)
Deleted them and now there are 64 more, dated 2018, 2017, 2016?
Verified the filter, looks good.
Verified Immediately delete and other settings under expunge.
Why is old spam piling up on Gmail server spam folder? What setting am I missing?