Unique ID for this message.
Alias for "message_id".
Subject or title of message.
Email address or mobile number (if SMS) the message was sent to.
Flag indicating if the message was sent as SMS or email.
Timestamp for when message was sent.
The actual message. May contain HTML.
Reply to address of email sent.
Comma-separated list of email addresses carbon copied.
Name of the person who sent the message.
Contains list of APIFile objects, representing attachements sent as part of the message (return from GET, not POST (yet))