Electronic Mail (email)

• Send Messages Across the Internet
• Developed in 1970s as Extension to FTP
• Originally Text Only
• Extended by Multipurpose Internet Mail Extensions (MIME)

Email Protocols

• Simple Mail Transfer Protocol (SMTP)
• Post Office Protocol (POP3)
• Internet Message Access Protocol (IMAP)
• Exchange ActiveSync

Email Server Components

• Mail Transfer Agent (MTA)
• Mail Delivery Agent (MDA)
• IMAP/POP/Webmail Server

Image Source: Wikipedia

cis527@cis527russfeldpuppet:~$ telnet mail.servergrove.com 110
Trying 69.195.222.232...
Connected to mail.servergrove.com.
Escape character is '^]'.
+OK POP3 ready
USER test@beattieunioncemetery.org
+OK
PASS uns3cur3
+OK logged in.
STAT
+OK 2 5580
RETR 1
+OK 4363 octets follow.
Received: (qmail 11929 invoked from network); 26 Feb 2016 16:16:14 +0000
Received-SPF: none (no valid SPF record)
Received: from mx-mia-1.servergrove.com (69.195.198.246)
  by sg111.servergrove.com with SMTP; 26 Feb 2016 16:15:43 +0000
...
...
...
DELE 2
+OK message 2 deleted
QUIT
+OK Bye-bye.