SMTP
Simple Mail Transfer Protocol
The protocol for sending email between servers.
SMTP is the standard protocol for sending and relaying mail between servers, designed without built in authentication or encryption in its original form. That openness enables spoofing and abuse, which is why layered controls such as SPF, DKIM, and DMARC validate sending sources, while STARTTLS adds transport encryption. The exam pairs SMTP with these email authentication mechanisms and contrasts it with retrieval protocols like POP3 and IMAP that clients use to read mail.
Looking SMTP up is step one. Getting tested on it is step two.
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