Re: doubling addresses when following up

[Toby Speight <Toby.Speight@streapadair.freeserve.co.uk>]

Vladimir> Vladimir V. Volovich <URL:mailto:vvv@vvv.vsu.ru>

0> In article <m34sece457.fsf@vvv.vsu.ru>, Vladimir wrote:

Vladimir> suppose that some message has headers
Vladimir> To: someone@domain.com
Vladimir> Reply-To: SomeOne@domain.com
Vladimir>
Vladimir> When i followup to this message, gnus puts both addresses (one
Vladimir> to To:, and one to Cc:).  But these addresses differ only by
Vladimir> case.  Do RFCs say that email addresses are case-insensitive?

The local-part of an address is case-sensitive as far as transmission is
concerned (though the two addresses may be delivered to the same mailbox,
a mail agent must assume they are as different as <some-one@example.com>
and <some.one@example.com>).  In a past life, I once used this for
filtering mail based on which case variant it was addressed to (with
case-insensitive delivery, and no "plussing" facility).

The domain-name, though, is case-insensitive, so <some-one@example.com>
and <some-one@Example.COM> refer to the same mailbox.

The relevant RFC is RFC 822 <URL:http://www.ietf.org/rfc/rfc0822.txt>,
which says:

#>      3.4.7.  CASE INDEPENDENCE
#>
#>         Except as noted, alphabetic strings may be represented in  any
#>         combination of upper and lower case.  The only syntactic units
#>         which requires preservation of case information are:
#>
#>                     -  text
#>                     -  qtext
#>                     -  dtext
#>                     -  ctext
#>                     -  quoted-pair
#>                     -  local-part, except "Postmaster"
#>
#>         When matching any other syntactic unit, case is to be ignored.
#>         For  example, the field-names "From", "FROM", "from", and even
#>         "FroM" are semantically equal and should all be treated ident-
#>         ically.
#>
#>         When generating these units, any mix of upper and  lower  case
#>         alphabetic  characters  may  be  used.  The case shown in this
#>         specification is suggested for message-creating processes.
#>
#>         Note:  The reserved local-part address unit, "Postmaster",  is
#>                an  exception.   When  the  value "Postmaster" is being
#>                interpreted, it must be  accepted  in  any  mixture  of
#>                case, including "POSTMASTER", and "postmaster".