Folks,
[Local-part. Case sensitivity. Globally opaque. Where to interpret.]
I'm fixing the email-arch draft, according to the various notes that point out
errors, confusion or poor wording. But I'm stymied by the several notes on the
topic of local-part, some of which discussed language or issues that seem to
differ from what is in email-arch.
Anyhow, here's what exists now:
RFC 5321
--------
2.3.11. Mailbox and Address
...the local-part MUST be
interpreted and assigned semantics only by the host specified in the
domain part of the address.
/////
2.4. General Syntax Principles and Transaction Model
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
...
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.
RFC 5322
--------
3.4.1. Addr-Spec Specification
The local-part portion is a domain-dependent string. In addresses,
it is simply interpreted on the particular host as a name of a
particular mailbox.
email-arch
----------
<t>The portion to the left of the at&nbhy;sign contains a
string that is globally opaque and is called the
<local&nbhy;part>. It is to be
interpreted only by the entity specified by the address's
domain name. Except as noted later in this section all
other entities MUST treat the
<local&nbhy;part> as an uninterpreted
literal string and MUST preserve all of its original
details. As such its public distribution is equivalent to
sending a Web browser "cookie" that is only interpreted
upon being returned to its creator.</t>
I think the current text in the draft accurately reflects the scope and formal
semantics of local-part. The draft does not confront the apparent contradiction
between "MUST BE treated as case sensitive" and "case sensitivity of mailbox
local-parts impedes interoperability and is discouraged" in RFC 5321.
Since the latter is not explicitly normative, I thought it acceptable for
email-arch to stick with the formal view.
If someone thinks email-arch should have different text on this topic, please
suggest some.
d/
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net