HTC Desire User Manual page 107

Messages 107
Priority setting
Set the message priority of SMS messages sent
Send callback number
Enable your phone to include a number with the text message to
allow the recipient to call you back by pressing the SEND button.
Callback number
Set the callback number.
MMS settings
Delivery reports
Select this option to receive a report on the delivery status of your
message.
Auto-retrieve
Select this option to automatically retrieve all your MMS messages
completely. When selected, the MMS message header plus the
message body and attachments will automatically download to your
phone. If you clear this check box, only the MMS message header will
be retrieved and shown in your All messages screen.
Priority setting
Set the message priority of MMS messages sent.
Maximum message size
Set the maximum file size of an MMS message. The MMS message will
not be sent out if it exceeds the file size set here.