I can't delete emails

I've been unable to delete emails from my macbook. When I try I get the message
The message “Action Required to Activate Membership for Mac-Forums.com” could not be moved to the mailbox “Trash — Verizon”
I've tried dragging, delete button and action via the toolbar. This all started about a week ago when an email got hung up.

I'll take any ideas/suggestions. I need to clean out my inbox.