"Not implemented" error downloading attachments.
Please make sure you are configured in ActiveSync mode only, or if this is an Exchange 2007 server without ActiveSync enabled, please make sure you are in Exchange 2007 mode and not Exchange 2003 mode. This error will occur if you are trying to connect to an Exchange 2007 server in Exchange 2003 mode. From the Settings screen Account tab, press the quick configuration button and follow the prompts, selecting either ActiveSync or Exchange 2007 on the protocols page.
To find Quick Configuration,