Computer Networking › Section B · The application layer › Topic B.3
Electronic mail
Email is one of the internet's oldest applications and still one of its busiest. Unlike the web, it relies on several protocols working in relay: one to move messages between servers, others to let people read them, and DNS records to find servers and check who really sent a message.
In this topic
- The parts of the email system
- The journey of a message
- Inside an SMTP session
- Worked example: reading an SMTP dialogue
- Message format: headers and envelope
- MIME: attachments and other languages
- Worked example: sending a photo attachment
- Submission and encryption in transit
- Reading mail: IMAP, POP3 and webmail
- Checking the sender: SPF, DKIM and DMARC
- Common mistakes to avoid
- Key takeaways
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