The usual advice to such queries is to say that while this is possible via the built-in '''Tools|Message Filters''', this is not generally useful, as you will forever be adding senders' addresses to your filters, as spammers generally do not repeatedly use the same address to send. True, if you have persistent repeat senders where for whatever reason you cannot or choose not to unsubscribe, then a Message Filter can be effective. But for general spam, it's better to train the inbuilt Junk filter by marking these messages as Junk. This doesn't have immediate effect, but with time, you train it to recognise patterns in the unwanted messages. https://support.mozilla.org/en-US/kb/organize-your-messages-using-filters https://support.mozilla.org/en-US/kb/thunderbird-and-junk-spam-messages I would add to the guidance about Message Filters that if you right-click the "from address" in the message header, you will see an option to create a filter based on this address.