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

2007-09-10 23:36:19

On Mon, Sep 10, 2007 at 09:26:36PM -0700, Timothy J. Miller wrote:
 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.

RFC 2822, section 3.4.1:

"The local-part portion is a domain dependent string."

My interpretation of that is "Don't touch it. At all. It's not yours."

 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 

Probably not a good assumption in general, at least for MTAs:

RFC 2821, section 2.4:

"The local-part of a mailbox MUST BE treated as case sensitive. Therefore,
SMTP implementations MUST take care to preserve the case of mailbox

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

I think "no", based on the citations above. I do empathize with you about the
particular problem you have. I've seen agents change
Blake(_dot_)Ramsdell(_at_)example(_dot_)com to 
BLAKE(_dot_)RAMSDELL(_at_)EXAMPLE(_dot_)COM on more than one

Blake Ramsdell | Sendmail, Inc. |

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