On Mon, Nov 10, 2025 at 04:59:49PM +0100, Tobias Fiebig via mailop wrote:
> I just encountered a mailto: URI with an unencoded white space, i.e.:
>
> """
> mailto: [email protected]
> """
The I would ignore that space. Was this in the conext of a DMARC or
other DNS record? It could, for example, result from sloppy
concatentation of multiple TXT record component character strings:
some.fqdn.example. IN TXT "... mailto:"; "[email protected]; ..."
that incorrectly adds spaces between the components when producing a
single result.
> Now, RFC6068 says that "Whitespace and comments within <local-part> and
> <domain> MUST NOT be used. They would not have any operational
> semantics."
That's a requirement for the creator of the URI, not a requirement to
reject violations, if you're able to tolerate the space without too
much trouble, do so, if not, you can ignore or reject the non-conformant
input as most appropriate.
> Now I am wondering, though, how an implementation should treat such a
> whitespace.
As they see fit. The input lies outside the specification, and it is up
to the implementation to choose to play BoFH or adopt a more forgiving
posture.
--
Viktor. 🇺🇦 Слава Україні!
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