SMTP does not have a draft concept. You should use IMAP instead.
Use TIdIMAP4 to log in to your GMail account, call its SelectMailBox() method to select the draft folder, and then call one of the AppendMsg...() methods to store the draft letter in the folder as needed.
If you want to make changes to the draft before sending it, you will need to extract the current draft from the folder (one of the Retrieve...() or UIDRetrieve...() methods) and edit as necessary, and then delete the current draft from the folder (method DeleteMsgs() or UIDDeleteMsg() ) and add a new draft to the folder.
To send a project, you will need to extract and delete it from the draft folder, and then use SMTP to send.
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