Here’s a nice hack I found on XDA in order to synchronize your emails and attachments (for attachments there is an option anyway to store attachments on storage card) to a storage card on a Windows mobile based pocket pc or smartphone.

1) First you need to create a folder called Inbox under \Storage Card which can be done from Activesync(on the desktop)—>Explore—>My Windows Mobile based device—>Storage card. Then create a sub folder under the Inbox folder called Attachments.

2) Download and install a free registry editor like PHM Registry Editor

3) Browse to HKEY_CURRENT_USER\Software\Microsoft\MAPI in the registry explorer.

4) We need to create two String Values under this key:

a) Create a String Value with name “AttachPath” (exclude the quotes) and String Path “\Storage Card\Inbox\Attachments” (Note the single back slash)
b) Create another String Value with name “PropertyPath” (exclude the quotes) and String Path “\Storage Card\Inbox”

Note: The values are Case Sensitive.

5) Soft reset your device

Now all your Inbox emails and attachments will sync to the Storage Card. This has been tested to work with Windows Mobile 2003 and Windows Mobile 5.0 pocket pc and smartphone.

Disclaimer: I don’t take any reponsibility for this hack. You might need to hard reset the device if something goes wrong. And it might be a slow process.