15. A message processing system, comprising: a sender reputation database that associates information identifying senders of electronic mail messages with reputation score values for the senders; one or more messaging devices coupled to the sender reputation database through one or more networks, wherein each of the messaging devices comprises: one or more processors; an HTTP proxy server hosted on one or more of the one or more processors; an SMTP mail transfer agent that is coupled to the HTTP proxy server; a local database that stores records that associate message sender identifying information with copies of URLs received in electronic mail messages from the senders; electronic mail processing logic that comprises one or more sequences of instructions which, when executed by the one or more processors, cause the one or more processors to perform the steps of: receiving an electronic mail message that comprises one or more hyperlinks; determining sender information that identifies a particular sender of the electronic mail message; creating and storing a record in the local database that associates the sender information with each of the one or more hyperlinks; receiving a request to access a specified hyperlink among the one or more hyperlinks; retrieving, based on the specified hyperlink, the record; retrieving, from the sender reputation database based on the sender information associated with the specified hyperlink, sender reputation information associated with the sender; determining, based on the sender reputation information, a particular action among a plurality of allowed actions; issuing a network request to access the specified hyperlink only when the particular action is allowing user access to the specified hyperlink.
15. A message processing system, comprising: a sender reputation database that associates information identifying senders of electronic mail messages with reputation score values for the senders; one or more messaging devices coupled to the sender reputation database through one or more networks, wherein each of the messaging devices comprises: one or more processors; an HTTP proxy server hosted on one or more of the one or more processors; an SMTP mail transfer agent that is coupled to the HTTP proxy server; a local database that stores records that associate message sender identifying information with copies of URLs received in electronic mail messages from the senders; electronic mail processing logic that comprises one or more sequences of instructions which, when executed by the one or more processors, cause the one or more processors to perform the steps of: receiving an electronic mail message that comprises one or more hyperlinks; determining sender information that identifies a particular sender of the electronic mail message; creating and storing a record in the local database that associates the sender information with each of the one or more hyperlinks; receiving a request to access a specified hyperlink among the one or more hyperlinks; retrieving, based on the specified hyperlink, the record; retrieving, from the sender reputation database based on the sender information associated with the specified hyperlink, sender reputation information associated with the sender; determining, based on the sender reputation information, a particular action among a plurality of allowed actions; issuing a network request to access the specified hyperlink only when the particular action is allowing user access to the specified hyperlink. 17. A system as recited in claim 15 , wherein the record is stored in a local database in a messaging apparatus that comprises an SMTP mail transfer agent and an HTTP proxy.