A few months ago, 1and1.com must have changed the protocol for logging in. At the time, I was using Firefox (and posted about that here: http://xnotifier.tobwithu.com/dp/node/3160, although a solution was never found).
Did you ever try the POP3 or IMAP scripts on Firefox version of X-Notifier to access 1&1 ? https://help.1and1.com/e-mail-and-office-c37589/1and1-mail-basic-c37590… As you probably know, Chrome does not support POP3/IMAP ...and newer 4.x versions of X-Notifier on Firefox won't either nor custom scripts. If no other script expert steps up, I'd think you'll just have to try sending the test account to the developer again, until you get a response one way or another.
Ironically?
Did you ever try the POP3 or IMAP scripts on Firefox version of X-Notifier to access 1&1 ?
https://help.1and1.com/e-mail-and-office-c37589/1and1-mail-basic-c37590…
As you probably know, Chrome does not support POP3/IMAP ...and newer 4.x versions of X-Notifier on Firefox won't either nor custom scripts.
If no other script expert steps up, I'd think you'll just have to try sending the test account to the developer again, until you get a response one way or another.