Your security software is creating the folder.Any email you flag as spam will go into your Junk folder because you already received the email and that's the folder Thunderbird uses. That folder will be created if it does not exist. In other words, any spam received and considered spam from the server end will be placed in the folder that is expected. Most email servers will mirror whatever folders expected in Thunderbird.The reasons for these different folders are, to be honest, a bit vague or overly complicated, and we couldn't find any official documentation on this problem, but we do know, for what it's worth, that Spam, Bulk Mail, and Junk are synonymous. In this guide, we look at the reasons and solutions. We've seen times where an additional folder, called spam mysteriously appears. Mozilla Thunderbird is one of the better free email clients available with built-in spam filters.
