I'm having this issue on my new HTC Magic. Firmware 1.5 Baseband 62.505.20.17U_188.8.131.52I Kernel 2.6.27-00393-g6607056 Build CRC1 Running on Vodafone in the UK. Type in a known email address in to the TO: field and select the address that pops up. The full email address is entered into the TO: field followed by a comma for the next address. Moving onto the next field, Subject:, causes the TO: field to clear, leaving behind the trailing comma separator/s.