Originally Posted by
dark_horse
From a purely technical perspective (and by this I mean going down into nuts-and-bolts Internet protocols), e-mail addresses should always be lower case.
Going into the nuts and bolts that is not quite correct.
The key document is RFC 2821 (
here) and the key paragraph is:
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. Mailbox
domains are not case sensitive. 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.
So
[email protected] is the same as
[email protected] but might differ from
[email protected]