SMTP(S)

Simple Mail transfer Protocol

InBound Mail = POP3(S) - IMAP(S)
OutBount Mail = SMTP(S)

• Standard mechanism for sending emails
• Authentication optional
  • But definitely recommended
  • In the past it lead to a lot of spam
• Clear text
• TCP 25 / TLS 587
  • You can still do hashing
  • Hashes will be protected by the use of TLS
  • TLS tunnel will secure your credentials
• Relaying capabilities
  • You may have a server mail environment where you send all your email to, that server will be responsible for the delivery, that's relaying
• MX Records point here!

SMTP Overview

• Send a message to you@pearson.com
• Looks at the domain name and performs an MX Record
  • In the Domain Name Service (DNS)
    • An MX Record stands for Mail Exchanger
      • Points to the IP address of the Mail Server
    • An A record matches an IP to a domain with IPv4
    • An AAAA record matches an IP to a domain with IPv6
• Do a DNS lookup through UDP port 53
  • Where is the MX record for pearson.com?
  • If you have mail to be delivered to anybody, send it to the IP address that the MX record says
    • At this point we are going to connect to that server through the default port number for SMTP (25)