Lines & dot transparency
05SMTP uses CRLF line endings and a single-dot line to mark the end of DATA. Dot-stuffing preserves literal leading dots.
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
DIAGRAM§ 4.5.2 ↗
RFC 5321 · § 4.5.2EXAMPLE
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Terminate DATA separately.
The standalone dot line ends content transfer and is not part of the delivered message.
Protocol participantThreat or exceptionProtocol controlSimplified drawings · precise section references
Read the updated RFC section ↗
Escape content so it cannot impersonate the delimiter.
- Lines end in CRLF; a line containing only a dot terminates DATA.
- The sender prepends a dot to each content line that begins with a dot.
- The receiver removes the extra leading dot from non-terminator lines.
Message framing is distinct from MIME encoding and from optional extensions that provide a different transfer method. A bare LF is not the defined SMTP line terminator.
Read the RFC section ↗Diagrams simplify the RFC. Read the linked sections for complete requirements.
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