operation of SMTP. Emoil E-moil Server Server Email client User IMAP E-mail client User MS MS Local UA POP3 MS client UA Local client MS UA SMTP UA POPЗ MTA MTA server server ISP TCP TCP LAN ISP...

Q4: B: Explain the operation of the SMTP protocol using a flowchart.

Extracted text: operation of SMTP. Emoil E-moil Server Server Email client User IMAP E-mail client User MS MS Local UA POP3 MS client UA Local client MS UA SMTP UA POPЗ MTA MTA server server ISP TCP TCP LAN ISP network prolocol stack LAN protocol stack prolocol IP IP IP protocol stack DL/PHY DL/PHY stack Global Internet backbone Site/campus LAN ISP network User agent Message transfer system User agent post office protocol POP SMTP ISP message store (contains a queue of mail to be sent and an IN mailbox for each of its local users) MS %3D simple mail transfer protocol %3D Internet service provider MTA = message transfer agent = user agent DL/PHY = data link/physical layer UA %3D Figure 2 Protocol stack to support e-mail over the Internet Email-2