Mail associating method and device

An embodiment of the invention discloses a mail associating method and a mail associating device. The mail associating method comprises the steps of: acquiring mail metadata when sending or forwarding a mail, creating a session, and establishing association of the session and a sent mail ID; adding an associated mail ID to a replied mail when replaying the mail, acquiring replied mail metadata, and associating a replied mail ID to the session with which the associated mail ID is associated; acquiring receiving mail metadata when receiving a mail, determining whether the receiving mail metadata comprises the associated mail ID, and if so, then associating a received mail ID with the session with which the associated mail ID is associated; if not, then creating a session, and establishing association between the session and the received mail ID; and acquiring and displaying the mail metadata according to the sent mail ID and/or the replied mail ID and/or the received mail ID which are/is associated with the session.