Also, if you use Gmail, get to the web interface and click off a few as spam.
After reading the information in https://support.mozilla.org/en-US/kb/thunderbird-and-junk-spam-messages#w_training-the-junk-filter, it remained unclear to me whether Thunderbird's filtering system will prevent any future emails from appearing in my Inbox from a sender once an email from him/her has been marked as Junk.
Or is it that the filtering system will put a block after a certain number of emails from a particular sender are marked as junk?.
Or is it that the filtering system will merely put the junk flag for a sender's all future mail once his/her email has been marked as junk but never prevent that person's email from appearing in the Inbox?

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