Improve email address normalization

[RohanNagar]

Improve email address normalization

[RohanNagar]

Additionally, RFC 6530 provides a lot of good detail on internationalization of email addresses. In particular regarding the local-part,

In general, it is wise to support addresses in Normalized form,
using at least Normalization Form NFC. Except in circumstances in
which NFKC would map characters together that the parties
responsible for the destination mail server would prefer to be
kept distinguishable, supporting the NFKC-conformant form would
yield even more predictable behavior for the typical user.

and

Unnormalized strings are valid, but sufficiently bad practice
that they may not work reliably on a global basis. Servers
should not depend on clients to send normalized forms but
should be aware that procedures on client machines outside the
control of the MUA may cause normalized strings to be sent
regardless of user intent.

Along these lines, providing an option to normalize the local-part according to Normalization Form NFC or NFKC could be useful.

The difficulty of implementing this remains to be seen.