Sender Policy Framework

DNS/Label

Each node in DNS has a label. The root node has an empty label. All other nodes have a label of at least 1 character and at most 63 characters long. Examples are: "com", "org", "net", "example", "provider", and so on.

Nodes that have the same parent are sometimes called sibblings. Such nodes cannot have the same label. Example: if two nodes have the same parent node labeled "com", they cannot both be labeled "example".

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Sender Policy Framework

DNS/Label

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