This illustration is identical to the previous illustration; however some of the labeling is different. From left to right, we see: Alice, and a desktop computer labeled "Alice's agent;" this is followed by a blue arrow pointing to the right, labeled "SMTP;" this is followed by Alice's mail server, including a server, the message queue, and the three mailboxes; this is followed by a blue arrow pointing to the right, labeled "SMTP;" this is followed by Bob's mail server, including a server, the message queue, and the three mailboxes; this is followed by a blue arrow pointing to the right, labeled "POP3, IMAP, or HTTP;" this is followed by a desktop computer labeled "Bob's agent," and Bob.