Did you set thunderbird up as Pop or IMAP?
If the latter and you delete in thunderbird, it should replicate to other emails clients you have (i.e. webmail).
If you have it set to Pop, can you not delete the account and then set up again using IMAP?
I'm not sure as to grouping in webmail as I rarely use it, but can you not sort by sender rather than date and highlight the ones you want?
Please remember to mark Solved Posts with Best Answer. Doing so helps other customers and saves TalkTalk's Support Team time by only looking at unsolved topics. Thanks, Steve (a fellow customer).
