while viewing your emails, hit the menu button and select delete. the screen will change and you will see x buttons beside the emails. you can select each one or push the menu button again and select mark all to delete all of the emails.- evo 4g
1) I press menu button and 6 boxes pop up.. (delete is the top left one)
2) I press delete and check boxes appear down the right side of the screen next to each email message allowing me to check each one and on the bottom of the screen there is a delete button on the left and a cancel button on the right.
3) I press the menu button again and a Brightness Setting button now appears across the bottom of the touch screen...
Nothing at all that allows me to "mark all" or "select all" or "delete all"
The problem with POP3 is that it doesn't sync with your mail account in the cloud. So whatever you delete on the Tab doesn't delete on the ISP side (unless you have it set to remove messages from server). So if you delete the POP3 account from the Tab, it will download all the messages on the server side for the amount of days that you set for display, including the ones that you deleted on the phone but not the server.
This is why I moved everything to GMail. If I send an email out of POP3, it's trapped on the phone unless I CC myself. GMail syncs all deletions and sent items to the cloud.