For SSL-imap it's imaps://. For some IMAP servers, I think you can replace @ with % in the URL like this:

imaps://corion%corion.net@imap.corion.net
[download]

... would try to log in as corion%corion.net on imap.corion.net, and I think some IMAP servers understand that by %corion.net you really meant @corion.net.