junk mail
I keep having Thunderbird put emails from a realty company in the Junk Mail folder. I have the company in all of my address books, I have a filter made from the sender instructing Thunderbird to put emails FROM this sender into my inbox, and have "Marked as Not Junk" easily over a hundred times. Yet it still keeps putting them in the junk folder. What also confuses me is that I have two accounts. One from my ISP, and one gmail account. I get emails from this sender sent to both accounts, and the gmail one leaves the messages in my inbox. It's only the one from my ISP that puts it in the junk folder.
Wšykne wótegrona (1)
It seems your ISP's spam filter is doing this. I suggest checking their settings.