Since bugzilla uses email addresses as usernames, and email addresses are by nature not case sensitive, bugzilla should never treat usernames or email addresses as case sensitive. e.g. when adding someone to the cc: list of an issue, if I put in the address edward_blazek, it's rejected as not a bugzilla user. If instead I put Edward_Blazek, it takes it and happily sends the email. This is broken. I should not have to know how a user capitalized their email address when creating a bugzilla account in order to cc: them on a bug.
This is indeed an issue and is part of the original design/code. I am marking this as an RFE and will definitely fix this as soon as release is done.
*** Bug 41371 has been marked as a duplicate of this bug. ***
I have spoken with the Bugzilla community and the consensus is to leave it the way it is due to email standards. 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 August 13, 1982 - 14 - RFC #822 Standard for ARPA Internet Text Messages 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". So from this I gather that the username portion of the email address should treated as case-sensitive and the domaim part as in-sensitive. It is true that most MTA's actually munge the address to make Dkl and dkl go to the same place.