What are RFCs and how do they govern email protocols?
RFCs (Requests for Comments) are technical specification documents that define how internet protocols work. Despite the name suggesting informality, RFCs are authoritative standards that email software must follow to interoperate correctly.
Key email RFCs include RFC 5321 (SMTP protocol), RFC 5322 (message format), RFC 7208 (SPF), RFC 6376 (DKIM), and RFC 7489 (DMARC). These documents specify exactly how email systems must behave, what headers mean, and how authentication works.
RFCs govern email by creating shared understanding. When your server implements SMTP according to RFC 5321 and the receiving server does the same, messages transfer correctly. Deviating from RFC specifications causes compatibility problems and may trigger filtering.
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