Identification of data structures

user
#ID_user PK	int
*name	varchar
*surname	varchar
*email_adress	varchar
*User_type	int

                                                                                 

Email
#ID_email PK	int
0* messagecontent	varchar
*ID_sender FK	int
*ID_receiver FK	int

Inbox
#ID_inbox PK	int
*ID_user FK	int
0 ID_email FK	int

Drafts
#ID_draft PK	int
*ID_Inbox FK	int
content_draft	varchar