The invention discloses an electronic seal system accessing a digital mailbox, including: a first acquisition module acquiring multiple identity information and enterprise information of a user; a second acquisition module acquiring multiple CA certificates and corresponding keys provided by multiple certificate authorities; an information authentication module performing physical or digital authentication on the identity and enterprise information based on the CA certificates, and generating authenticated identity and enterprise information; an electronic private/official seal generation module generating an electronic private seal and an electronic official seal of the user based on the authenticated information; application modules for enabling application functions; and a digital mailbox linking module linking the seal generation module and the application modules after the user logs into a digital mailbox.