[RCU] Usernames roundcube sends to servers

Michael Orlitzky michael at orlitzky.com
Sun Dec 20 18:22:13 CET 2009

Steve Perkins wrote:
> Pretty stupid thread.
> Everyone in the whole world knows that email addresses are case
> insensitive. Why on earth would case matter? 
> Thats like having two domains, www.xyz.com compared to Www.xyz.com
> Like I said, pretty stupid.

What the hell is everyone talking about?

 From RFC 5231 (and the previous ones):

    Verbs and argument values (e.g., "TO:" or "to:" in the RCPT command
    and extension name keywords) are not case sensitive, with the sole
    exception in this specification of a mailbox local-part (SMTP
    Extensions may explicitly specify case-sensitive elements).  That is,
    a command verb, an argument value other than a mailbox local-part,
    and free form text MAY be encoded in upper case, lower case, or any
    mixture of upper and lower case with no impact on its meaning.

    * The local-part of a mailbox MUST BE treated as case sensitive. *

    Therefore, SMTP implementations MUST take care to preserve the case
    of mailbox local-parts.  In particular, for some hosts, the user
    "smith" is different from the user "Smith".  However, exploiting the
    case sensitivity of mailbox local-parts impedes interoperability and
    is discouraged.  Mailbox domains follow normal DNS rules and are
    hence not case sensitive.

(emphasis mine). If you can deliver mail case-sensitively, you should be 
able to /retrieve/ mail case-sensitively. If your LDA/IMAP server 
override this (per the recommendation), then so be it; but at that point 
the case-folding is no longer the responsibility of the client.
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