Most probably, I make a real stupid mistake, but I can't install Mail for Exchange V 2.5.5 on my E90. The installation process stops and the phone says "Aktualisierungsfehler" which could be translated with "updating error".
I found a V 2.3.0 on download! that I could install without any problems. When I try to update now, there is the "Aktualisierungsfehler" message again.
I'd be happy if anybody could help me! Thank you very much in advance.