Figure 11-5: E-Mail standards Sender's mail Receiver's mail Server Server Message Body Format Standard Sending ReceIving E-Mail RFC 822 or 2822 E-Mail Client Message HTML body Client UNICODE
11 Figure 11-5: E-Mail Standards Sending E-Mail Client Receiving E-Mail Client Sender’s Mail Server Receiver’s Mail Server Message RFC 822 or 2822 HTML body UNICODE Message Body Format Standard
I Figure 11-4: E-Mail E-Mail standards Receiver must understand sender's message Message body standards RFC 822 and rfc 2822 for all-text bodies HTML bodies with fancy text and graphics UNICODE for characters in any language 12
12 Figure 11-4: E-Mail • E-Mail Standards – Receiver must understand sender’s message – Message body standards • RFC 822 and RFC 2822 for all-text bodies • HTML bodies with fancy text and graphics • UNICODE for characters in any language
Figure 11-6: Interactions in the simple Mail Transfer Protocol ( SMTP) Actor SMTP Command Comment Client SMTP None Connects to server Process Via tcP When a tcP connection Server SMTP Process 220 Mail Panko. Com Ready is opened, the server signals that isis ready Client SMTP Client asks to begin Process HELO Voyager. cba. Hawaii. edu sending a message Gives own identity Server signals that it Server 250 Mail Panko. com is ready to begin receiving a message 13
13 Figure 11-6: Interactions in the Simple Mail Transfer Protocol (SMTP) Actor SMTP Command Comment Server SMTP Process 220 Mail.Panko.Com Ready When a TCP connection is opened, the server signals that is is ready. Client SMTP Process HELO Voyager.cba.Hawaii.edu Client asks to begin sending a message. Gives own identity. Server 250 Mail.Panko.Com Server signals that it is ready to begin receiving a message. Client SMTP Process None Connects to server Via TCP
Figure 11-6: Interactions in the Simple Mail Transfer Protocol (SMTP) Actor SMTP Command Comment Client MAIL FROM: Bob@ Client identifies the sender voyager. cba. hawaii. edu (mail author, not SMTP process) Server 250 OK Accepts author. However may reject mail from others ClientRCPTTO:Ray@Panko.comIdentifiesfirstmailrecipient Server 250 OK Accepts first recipient 14
14 Figure 11-6: Interactions in the Simple Mail Transfer Protocol (SMTP) Actor SMTP Command Comment Server 250 OK Accepts author. However, may reject mail from others. Client RCPT TO: Ray@Panko.com Identifies first mail recipient. Server 250 OK Accepts first recipient Client MAIL FROM: Bob@ voyager.cba.hawaii.edu Client identifies the sender (mail author, not SMTP process)
Figure 11-6: Interactions in the Simple Mail Transfer Protocol (SMTP) Actor SMTP Command Comment ClientRcptTo:Lee@panko.com Identifies second mai recipient Does not accept second Server 550 No such user here recipient. However will deliver to first recipient Client DATA Message will follow 354 Start mail input; end with Gives permission to send Server <CRLF> <CRLF> message 15
15 Figure 11-6: Interactions in the Simple Mail Transfer Protocol (SMTP) Actor SMTP Command Comment Client DATA Message will follow. Server 354 Start mail input; end with <CRLF>.<CRLF> Gives permission to send message. Client RCPT TO:Lee@Panko.com Identifies second mail recipient. Server 550 No such user here Does not accept second recipient. However will deliver to first recipient