Sender Policy Framework

FAQ/Underscore in DNS

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== Whoa, that's an underscore in spf. I thought you could only have letters, numbers, and dashes in domain names, no underscores?		== Whoa, that's an underscore in spf. I thought you could only have letters, numbers, and dashes in domain names, no underscores?
Apparently underscores are now okay. See [http://www.faqs.org/rfcs/rfc2181.html RFC2181 section 11].		Underscores are okay in domainnames, just not in hostnames.

Underscores create a new secret dimension: that's the only way to guarantee you don't collide with an existing subdomain. SRV records use underscores for exactly this reason. Actually SPF doesn't use underscores anymore because, although legal, many providers didn't support them. Other related technlogies, such as [http://mipassoc.org/dkim/ DKIM], do use them however.		This is not really SPF-specific, please see [[DNS/Underscore]] for more information.

Whoa, that's an underscore in spf. I thought you could only have letters, numbers, and dashes in domain names, no underscores?

Underscores are okay in domainnames, just not in hostnames.

This is not really SPF-specific, please see DNS/Underscore for more information.

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Sender Policy Framework

FAQ/Underscore in DNS

Whoa, that's an underscore in spf. I thought you could only have letters, numbers, and dashes in domain names, no underscores?

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