Maybe it works again after a few days. Also they keep updating Grepolis, so let's hope they solve this problem for us

And I thought of one more thing you could try. Have you already cleaned your internet cache?
A new version is also ready:
Version: 2.0.2 Date: 17-08-2011
New features:
-Improved email notifications. (Donators only)
-Added button to test email feature.
Known bugs:
-All versions are having problems handling accounts with more then 30-40 towns. I’ll have to make a new interface to fix this problem.
~Uthar