I've got a gmail connection which works fine, and a pop mail connection to my ISP. It says on the status line Connected to pop.rcn.com... but nothing ever happens, no new mails download.
Yet Thunderbird generally isn't hung up. I can go through old rcn emails, get new gmail emails, etc. Just can't pull any new ones from rcn, and there are no error messages. And I can send emails through that server, simply can't download them. Verified, of course, with webmail access that there are new emails present for downloading.