Enabling recipients to share tags that they associate with received e-mails includes receiving an e-mail from a sending user addressed to a receiving user, the e-mail including a header and a body and being capable of supporting attachments to the e-mail that are distinct of the body. The receiving user is enabled to perceive the e-mail and associate at least one tag with the e-mail, the at least one tag being a textual descriptor for the received e-mail distinct from the header, body, and attachments of the received e-mail. The received e-mail and the at least one tag are stored in a data store associated with the receiving user. The at least one tag is propagated to at least one of the sending user and another recipient of the e-mail to whom the sender sent the e-mail.