Filesystems and case-insensitivity [LWN.net]

Filesystems and case-insensitivity

Posted Dec 7, 2018 11:45 UTC (Fri) by gioele (subscriber, #61675)
In reply to: Filesystems and case-insensitivity by Wol
Parent article: Filesystems and case-insensitivity

> I *still* have problems because users insist on knowing whether email addresses have capital letters or not (they are case-insensitive, for historical reasons, because a lot of the early systems mangled case).

These users are right: the local-part of an email address _is_ case sensitive. Only the domain is case insensitive.

RFC 5321, section 2.4 [1]:

> 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.

[1] https://tools.ietf.org/html/rfc5321#section-2.4

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Filesystems and case-insensitivity

Posted Dec 7, 2018 16:31 UTC (Fri) by smurf (subscriber, #17840) [Link] (1 responses)

Its cast must be preserved in transit but terminal MTAs are free to treat them as case insensitive. Most do, these days.

Filesystems and case-insensitivity

Posted Dec 8, 2018 23:37 UTC (Sat) by zlynx (guest, #2285) [Link]

Fedora's default Exim configuration did not make it insensitive. I had to add that myself because my server was rejecting a lot of mail, mostly from Gmail users randomly capitalizing things.

> lowercase_local:
> driver = redirect
> data = ${lc:${local_part}}