Re: login case sensitivity

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Am 07.09.2017 um 20:07 schrieb hw:
Gordon Messmer wrote:
On 09/07/2017 08:11 AM, Stephen John Smoogen wrote:
This was always
problematic because DNS hostnames and email addresses in the RFC
standards were case insensitive


Not quite.  SMTP is required to treat the "local-part" of the RCPT argument as case-sensitive, and to preserve case when relaying mail. The destination is allowed to treat addresses according to local policy, but in general SMTP is case sensitive with regard to the user identifier.

Last time I checked, RFCs said that local parts *should not* be case sensitive, and cyrus defaulted to treat them case sensitive, which is a default that usually needs to be changed because senders of messages tend to not pay any attention to the case sensitiveness of recipient addresses at all, which then confuses them like
any other error.

The relevant part from the RFC:

https://www.ietf.org/rfc/rfc5321.txt

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 (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.

Alexander
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