Calendar entries that live in Exchange 2010 cannot be edited After setting up mail and calendar synchronization with our Exchange server (Exchange 2010) and the built-in app, I cannot edit the entries in the Exchange calendar. Adding new entries works fine.

Comment #15 of a Google code issue shows an important hint. It works when the "primary E-mail address" is used when connecting to the account.

Could there be other reasons? How do I find the primary E-mail address (short of asking the system administrator)?
I was able to retrieve the primary e-mail address from my phone: In the details of an appointment, I was listed as attendee under an e-mail address different from the one the account was configured for, and the e-mail address of this attendee turned out to be my primary e-mail address.

I was unable to change the e-mail address for the existing account. After dropping and recreating the account using the primary e-mail address, I can now update details of all appointments on my device.