| Platform SDK: MAPI |
Before a message is saved, clients typically call the message's IMAPIProp::SetProps method to set a few properties in addition to the message text properties, attachment properties, PR_SUBJECT, and properties associated with the recipient list.
Set the PR_MESSAGE_CLASS property to a character string such as IPM.Note that describes the class of the outgoing message. Although clients should set PR_MESSAGE_CLASS on all outgoing messages, a default value is supplied by the message store provider if you do not set it. The default message class for outgoing messages is IPM.
Set the MSGFLAG_UNSENT flag in the PR_MESSAGE_FLAGS property. If desired, also set the MSGFLAG_READ and MSGFLAG_UNMODIFIED flags. Setting the MSGFLAG_UNMODIFIED allows a message under composition to simulate a delivered message. MSGFLAG_UNMODIFIED can only be set by clients before a message has been saved for the first time.
If you implement scheduling as a feature, set these properties on your message:
The PR_START_DATE and PR_END_DATE properties mark the beginning and end of an appointment, respectively.
The PR_OWNER_APPT_ID property contains an identifier that represents an appointment and can be used to schedule meetings. This identifier is an integer rather than an entry identifier.
When you are ready to make a permanent copy of an unsent message, call IMAPIProp::SaveChanges on the message and all of its attachments. If you intend to send the message right away, you do not need to call SaveChanges. The call to SubmitMessage internally saves the message as part of its processing.
When calling SaveChanges, it is a good idea to specify the KEEP_OPEN_READWRITE flag, which allows the message to be modified at a later time. Other settable flags include FORCE_SAVE, which indicates that the message or attachment should be closed after changes are committed, KEEP_OPEN_READONLY, which indicates that no further changes will be made, and the flag to allow the message store provider to batch client requests, MAPI_DEFERRED_ERRORS.
It is essential that you call SaveChanges for every attachment in the message before you call SaveChanges for the message. If you fail to save an attachment, the attachment will not be included with the message when it is sent and it will not appear in the message's attachment table. If you fail to save the message after saving all of the attachments, both the message and the attachments will be lost.
When SaveChanges is called, the message store provider updates the following properties:
Some message properties are typically supplied by clients or service providers when a message is created. If a client neglects to set them, it is up to the message store provider to update them at the time SaveChanges is called. For example, if a message's PR_ENTRYID and PR_RECORD_KEY properties were set when the message was created, they need not be modified at save time. However, message store providers that neglect to set them at message creation must set them the first time that SaveChanges is called.
If SaveChanges returns MAPI_E_CORRUPT_DATA, assume that the data being saved is now lost. Message store providers that use a client-server model for their implementation might return this value when a network connection is lost or the server is not running. Before returning an error to the user, try to write and save the data a second time by making a call to SetProps followed by another call to SaveChanges. If the data is cached locally, this should not be a problem. However, if there is no local cache or the second SaveChanges call fails, display an error to alert the user to the problem.