Re: [bidi] BIDI in mail addresses

I'd like to encourage the people coming from the bidi mailing list to
help us with the main question that IMAA is now facing: how to apply the
Stringprep bidi check.

The current draft applies it to the entire local part, which creates two
annoyances: FOO2 is not allowed (because it's right-to-left but does not
end with a strong RTL character), and owner-FOO is not allowed (because
it mixes strong LTR and strong RTL characters).

One alternative is to apply the bidi check to individual segments.
(IMAA already divides the local part into segments for other reasons.
Segments are delimited by non-alphanumeric ASCII characters.)  This
would allow owner-FOO, but would continue to disallow FOO2, and would
also disallow FOO2-BAR, which is allowed in the current draft.

Another alternative is to not apply the bidi check at all.  This would
allow all the cases mentioned, and would also allow things that the bidi
check was intended to protect us against, like 2FOOfooBARbar3.

We think that disallowing owner-FOO is sufficiently onerous that the
current draft needs to be changed, but it's not clear to us which of the
other two ideas has a better risk/reward tradeoff, or if they're both so
bad that we ought to try to think of something else.

AMC