CentOS - Sep 2017 - login case sensitivity

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.

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.

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