Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

Chapter 16. Electronic Mail and News > Simple Mail Transfer Protocol (SMTP)

16.2. Simple Mail Transfer Protocol (SMTP)

On the Internet, electronic mail exchange between mail servers is handled with SMTP. A host's SMTP server accepts mail and examines the destination address to decide whether to deliver the mail locally or to forward it on to some other machine. If it decides to deliver the mail locally, it recodes the mail headers and delivery address into the proper form for the local delivery program, and it then hands the mail to that program. If it decides to forward the mail to another machine, it modifies the headers and contacts that machine (usually via SMTP, but sometimes via UUCP or another protocol) and forwards the mail.

SMTP is a store-and-forward system, and such systems are well suited to firewall applications, particularly those using proxy services. In Chapter 9, Figure 9.2 shows how mail sent from an individual user's workstation is directed initially to a gateway system before leaving the user's own network. Mail entering a network goes to a gateway system on that network before being distributed to individual users on other hosts.


  

You are currently reading a PREVIEW of this book.

                                                                                                                    

Get instant access to over $1 million worth of books and videos.

  

Start a Free Trial


  
  • Safari Books Online
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint