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Vagueness re: case sensitivity of local-part in RFC2822.

2007-09-10 21:53:31
OK, this has been bugging me for a while now.

2822 says that the domain-part of an address is interpreted as a domain name, and the DNS RFCs say domain names are case-insensitive. But it looks to me like 2822 is silent on *local-part* case sensitivity.

Logic can take us either way; i.e., since RFCs are generally silent unless insensitivity is needed, local-part must be sensitive--or, alternately, since the RFC is silent in this case it's best to interpret for maximum compatibility, so local-part must be insensitive.

And most MTAs and MUAs in my experience treat local-part as case insensitive.

Except Apple Mail S/MIME processing. All other S/MIME MUAs I've tested go with case insensitive for S/MIME local-part address matching--but Apple Mail is case sensitive. This is a real pain in my neck, especially with the DoD PKI, where email addresses are not (yet) centrally provisioned, so case mismatches between the mail system and the PKI are common.

I can't get Apple to budge on fixing it because they've staked out the strict interpretation, despite the common interpretation otherwise and the demonstrable problems this causes. A fix 2822 would help, but I figured I'd ask the opinion of this list before I took things further:

Should the local-part of an RFC2822 addr-spec be interpreted as case- insensitive?


-- Tim

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