How Emails and Texts Work: SMTP, IMAP, POP, SMS and OTT
SMTP sends email; IMAP (which leaves mail on the server) is overtaking POP (which deletes it). Texts use SMS (160-character limit, works without internet) or internet-based over-the-top (OTT) services that can offer end-to-end encryption. CAN-SPAM and the TCPA govern marketing messages.
How this supports CIPP/US study
Use this lesson to identify the legal source, actor, data and activity before applying a rule to a scenario. Continue with the CIPP/US study guide.
| Protocol | Behavior |
|---|---|
| IMAP | Typically leaves messages on the server; enables synchronization across multiple devices and server-side search; increasingly common |
| POP | Typically deletes mail from the server; used less over time |
For sending, SMTP is most common. Texts began with SMS (160-character limit, can run on cell service without internet) and have shifted to over-the-top (OTT) services like iMessage, Signal, Telegram, and WhatsApp, which lack SMS limits and can provide end-to-end encryption.
CAN-SPAM (Chapter 11) requires commercial email marketing to honor opt-outs, and the Telephone Consumer Protection Act (TCPA) (Chapter 11) regulates marketing via text messages. Know which applies to email vs text.
Key terms - quick answers
What is “SMTP”?
What is “IMAP”?
What is “POP”?
What is “SMS”?
Sources and study method
This independent lesson uses active recall, spaced retrieval and scenario practice. Read the full study method.