You mention 'Spam' folder, so I'm assuming this is an imap mail account. Perhaps the server is filtering them into the 'Spam' folder and Thunderbird is just showing what is on server when spam folder synchronises. Logon to webmail account and see if that email address is in the spam settings/filtering section.

You could see if your settings in thunderbird are seeing email as potential spam and moving it.

Menu icon > Activity Manager Does it mention moving email to spam? You can use the time of move to spam to best guess which emails and number thereof were moved. If it says it moved eg: 1 and you have more than one then it is possible Thunderbird did not move it, but the server did.

• Right click on mail account in Folder Pane and select 'Settings'
• select 'Junk settings'
• I assume the address books are already selected, if not select them.
• uncheck checkbox 'Trust junk mail headers set by.....'
• click on OK

When you select the 'spam' email in spam folder, is there a message that says 'Thunderbird thinks this email is a scam' If yes, then this may explain why it is in Spam; you could turn this off. Menu icon > Options > Security > 'Email Scams' tab uncheck checkbox 'Tell me if the message I'm reading is suspected email scam' click on 'OK'

When you select the 'spam' email in spam folder, is there a message that says 'Thunderbird thinks this email is a junk mail'

Option: You could set up a Message Filter for the account Give filter suitable name Apply filter when 'getting new mail' and 'Filter before Junk Classification' 'From' 'contains' 'concreteplayground.com.au' Action: 'Move Message to' and select a suitable folder - not Inbox. click on OK Make sure filter is enabled.