HELP! CRAM-MD5 auth failed

[james-allen]

I'm wanting to move from my crappy hosting to a new shiny service and
need to migrate the mailboxes across. I am testing larch and keep
getting this error:

C:\>larch --from imap://mail.allen-mail.com --to imap://nas.james-allen.co.uk
-V debug --dry-run
Source username (mail.allen-mail.com): james
Source password (mail.allen-mail.com):
Destination username (nas.james-allen.co.uk): james
Destination password (nas.james-allen.co.uk):
[21:28:00] [debug] [<] connecting...
[21:28:03] [info] [<] connected to mail.allen-mail.com on port 143
[21:28:03] [debug] [<] authenticating using CRAM-MD5
[21:28:04] [debug] [<] CRAM-MD5 auth failed: AUTHENTICATE CRAM-MD5
Failed - The account you specified does not appear to have access to
this service.
[21:28:04] [debug] [<] authenticating using LOGIN
[21:28:04] [debug] [<] LOGIN auth failed: AUTHENTICATE LOGIN failed -
Invalid username or password.
[21:28:04] [debug] [<] authenticating using PLAIN
[21:28:04] [fatal] Net::IMAP::ResponseParseError: unexpected token
CRLF (expected SPACE) (cannot recover)
[21:28:04] [info] 0 message(s) copied, 0 failed, 0 deleted out of 0
total
[21:28:04] [debug] performing database maintenance

My Email clients have no problem connecting for IMAP with these
credentials.

Any clues?

James