There is an important difference, and a significant security implication, between spam and junk mail. I suspect that the developers who decided to replace the Junk folder with a Spam folder (Thunderbird v145) did not fully understand their distinctions.
Both folders serve essential purposes and should be reinstated in Thunderbird.
In this current, If I receive an unwanted or unsolicited email in my inbox, I am forced to classify it as spam as a means to stop it coming into my inbox in the future. This should be concerning because emails should be marked as spam only when there is a reason to believe they may be malicious. Many unwanted emails, however, are simply legitimate marketing messages from reputable businesses promoting their products or services.
A Junk folder is necessary to keep unwanted but harmless emails out of the inbox. Users may also configure their inboxes to accept messages only from approved senders (e.g., contacts). In such cases, expected but unapproved emails may still end up in the Junk folder, but this setup offers an important “saving grace”: it allows users to perform periodic reviews and recover legitimate messages that were filtered incorrectly.
Spam filters on mail servers, among other detection methods, monitor emails tagged as spam by mail clients and may block these messages or even entire domains from passing through their servers. This can have serious consequences for legitimate businesses. For example, they may need to send important communications to customers, but those customers may never receive them because the domain has been incorrectly flagged as malicious.
A Spam folder is therefore equally necessary to isolate unwanted and potentially malicious emails from both the inbox and the Junk folder. Marking emails as spam not only moves them out of the inbox but also signals to mail servers that these messages may be harmful.
