Problems Importing Mail From Large Mailboxes


I am using OS 10.4.1 and Mail 2.0. After downloading a plug-in for Mail, I started having major problems with Mail (couldn't send messages and had to force-quit in order to quit every time). To get a fresh version of Mail, I set up a new user and configured Mail to my liking. I copied the new Mail files into my old user account and copied my old mailboxes into the new Mailboxes folder. Rebuilding the mailboxes in Mail worked fine for most of the mailboxes, but not for the very large ones (ranging from approx. 100-3000 messages). For these mailboxes, Mail displayed 0 messages and a symbol looking like a restart button (circle with small vertical line coming from the top) appeared by the name of the mailbox. Restarting the computer didn't help. I tried importing the mailboxes instead, but that didn't work either. I read on this site that there is a size limit to the imports, so I split up the mailboxes into smaller chunks (by deleting messages from the Messages folder). When I imported these smaller mailboxes, I was able to view the messages again, HOWEVER, when I tried to copy these messages into a new mailbox to consolidate them again, they again became unviewable in Mail. Is there a way around this problem?

My technical level = low intermediate; prefer too simple over too complicated.

You claimed that your problems started after downloaded a plug-in. Which plug-in? Why didn't you try to fix the problem by removing the plug-in?