Joe wrote: > I'm fairly sure that neither the SMTP protocol nor exim in particular > distinguish cases in email addresses.
In the SMTP protocol, the local part of a mail address IS case-sensitive, the domain part is not. See RFC 5321, 4.1.2: | Local-part = Dot-string / Quoted-string | ; MAY be case-sensitive Obviously, it's a really bad idea to use case-sensitives local parts, as the RCC mentions further on: | While the above definition for Local-part is relatively permissive, | for maximum interoperability, a host that expects to receive mail | SHOULD avoid defining mailboxes where [...] | where the Local-part is case-sensitive. Exim will consider local-parts case-insensitive by default: | caseful_local_part | | By default, routers handle the local parts of addresses in a | case-insensitive manner, though the actual case is preserved for | transmission with the message. If you want the case of letters to be | significant in a router, you must set this option true. <https://exim.org/exim-html-current/doc/html/spec_html/ch-generic_options_for_routers.html> -thh
