I tried the advice from the WalGreens post, etc re 'the same file keep downloading dozen of times' + it worked OK... but now TBrd is marking all my new emails as 'junk'...

Is this a pop or imap mail account ? Do you have any 'Message Filters' which have an action to mark as junk? Are the emails in the Inbox or in the Junk folder ? Do they have a yellow flame coloured icon or just a greyed outline of a flame?

Please post image showing your current 'Junk settings' for that account. Right click on mail account name in Folder Pane and select 'Settings' Then select 'Junk Settings' Post image of the 'Junk Settings' Then click on the 'Global Junk Preferences' button - it opens 'Settings/Preferences' in a new tab Post image showing the 'Junk' section settings.

...it worked OK... but now TBrd is marking all my new emails as 'junk'...

I restarted my computer... LOL