Could someone have a look at ticket 1443200? http://trac.roundcube.net/trac.cgi/ticket/1443200
It appears that the error message returned by BincIMAP when requesting an invalid range of messages (1:0) isn't handled properly. Courier also generates an error, but does not exhibit the same problem.
I put a patch in the ticket that fixes it for me, although there could be a deeper issue, I added a simple sanity check that allows it to function as it should. I had it check for the case that is failing (1:0) but I suppose the more general case of the range n:m where n>m should also be tested.
If the simple check could be committed, it would at least let that many more people use RC without wondering why it won't let certain users login... :)
I have another BincIMAP issue, ticket #1483855, but it's much harder to solve. I'll see if there's any more I can do to help figure out how to best solve that one.
Jim