JAMES-4133 Add support for unicode adddresses as defined in RFC6532.

[arnt]

This adds Domain tests and does enough to parse unicode email addresses.

However, I'm not quite happy. This needs documentation changes, I wouldn't mind another few Domain tests, and I do want to investigate what's up with Jakarta and संपर्क@डाटामेल.भारत but haven't time to do that this week.

Consider it a WIP.

[chibenwa]

Hello @arnt

Thanks for this major contribution.

I did update #2724 with your changes and can happily say the SMTP-IN stack in James is RFC-6532 compliant :-)

However, I did face major issues as any modification (header for instance, but also the defensive copy done in the memory mail queue) causes the loss of the UTF-8 characters. This clearly see like a lack of support for RFC-6532 from jakarta.mail.internet.MimeMessage which James (sadly...) still heavily relies on. (quick checks tends to confirm this dependency do not support RFC-6532).

BTW I did turn the PR into a draft and add the ticket number into the title in order to make this clear.

Best regards,

Benoit TELLIER