How can I split an address list into two or more different lists in Thunderbird? I can't copy multiple email addresses from one list and paste them in another list, and I can't copy the entire list into a new location in the address list "tree". There should be a way to copy the list without having to retype each email address in the new list.

I need to split an address list so the recipient count is lower. My emails for an organization that I'm editor for are getting blocked or dumped by certain recipient email programs, and I'm suspecting that the recipient count is large enough to make the receiving email host think that the emails are spam.