OfficeTalk lets you assign any project task to one or more OfficeTalk users. Additionally, you may assign the same project task to remote OfficeTalk users, belonging to a remote workgroup, and to anyone to whom you can send mail. This includes users of Microsoft Exchange, with whom OfficeTalk communicates via MAPI forms. OfficeTalk provides a way for recipients of assigned tasks to report on their progress and the result is represented in the project.
If you assign a project task to a local or remote OfficeTalk user, then in both cases, they will be issued with a mail message informing them of the assignment and containing any instructions that were added. They will also receive a task in their personal task list which may be used to schedule time in their diary and to update the project with their progress on that task in terms of percentage completion.
If you assign a project task to a non OfficeTalk recipient, for example, to a contact (who has an e-mail address), then the recipient will also receive a mail message informing them of the assignment. The mail message that the recipient will receive is slightly different from the message sent out to OfficeTalk users. Firstly the message is a plain text message. It does not contain rich text formatting. Secondly, it contains a unique character sequence which allows the recipient to reply to the sender, providing task completion details, and lets OfficeTalk extract this information automatically and update the project accordingly.
If you assign a project task to a Microsoft Exchange user, then OfficeTalk sends the task assignment using a special Project Task Assignment form which Exchange is capable of displaying.
More:
Receiving a Project Task Assignment
Assigning Project Tasks To Ordinary E-Mail Users
Assigning Project Tasks to Microsoft Exchange Users