From: Ansgar Wiechers (no email)
Date: Sat Nov 21 2009 - 08:03:35 EST
On 2009-11-21 Jerry wrote:
> I know that this has nothing directly to do with Postfix; however, I
> figured the fastest way to get a serviceable answer would be here.
> I maintain a few Yahoo groups. I just received a bulletin from Yahoo
> regarding the updating of their 'Groups'.
> Also in this release is a fix for group moderators who were having
> issues approving pending messages via email. Moderators affected by
> this issue were using email clients that (in violation of internet
> standards) do not honor case in reply to addresses, meaning that they
> would turn upper case letters into lowercase. Since the codes that
> enable email moderation to work relied on the reply address being the
> exact sequence of characters we were expecting, email moderation
> commands did not work for these users. But we have now updated our
> code in a way that will enable email moderation to work for even these
> email clients, which should allow moderators to approve pending
> messages and members via email once again.
> I was, perhaps incorrectly, of the opinion that case was not relevant
> in e-mail addresses. I thought that there was an RFC that mentioned
> this; although I cannot find one that specifically mentions case
> folding on the reply to address.
> Is Yahoo's claim correct or are they simply trying to cover up for a
> problem on their end?
Quoting from chapter 2.4 of RFC 2821:
| 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. This
| is NOT true of a mailbox local-part. The local-part of a mailbox MUST
| BE treated as case sensitive.
-- "Abstractions save us time working, but they don't save us time learning." --Joel Spolsky