I have used SpamSieve for many years & so its worked away in the background - however without me noticing, the need to filter out spam seems to have disappeared over a period of time! I used to get 40 or 50 spam messages a day - you know the penis enlargement stuff or I am a Russian Princess & I want to marry you! This is now nil & even though I keep SpamSieve going it doesn’t seem to be needed. I have a collection of Gmail & Yahoo email accounts. Have these providers got better at attacking spam before it gets to me or maybe my IP provider is in on the act? Just curious.
Your ISP wouldn’t affect messages that are sent to Google or Yahoo addresses. Apple deletes some spam messages to mac.com/me.com/icloud.com addresses outright. As far as I know, Google and Yahoo do not do this. Any spam that they catch would be in the Spam or Bulk mailbox on the server.
Your ISP rejected the message from the forum notifying you that there was a new post in this thread. So perhaps it is rejecting a lot of other messages, too.