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<div class="">I have thought about this many times over the years and here are some of my thoughts -<br class="">
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A lot depends on when the validation is done. If it is done at registration time then I think it is possible to use regex to validate.<br class="">
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Take <a href="http://datamail.in" class="">http://datamail.in</a> http://电邮.在线 http://डाटामेल.भारत The user is explicitly selecting a language/script and thus constraining the Unicode characters which can be used for the local part.. For a particular language/script
the IDN is fixed for that language/script so that leaves just the local part/ mailbox name to validate. One could use a simple regex with a modern Unicode aware regex engine.<br class="">
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For a chinese local part then something like: \p{Han}+<br class="">
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or Hindi/Devanagari local part something like: \p{Devanagari}+<br class="">
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André Schappo</div>
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<div class="">On 12 Sep 2017, at 19:44, Don Hollander <<a href="mailto:don.hollander@icann.org" class="">don.hollander@icann.org</a>> wrote:</div>
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Please note that this is a Geeky post - so carry on if that’s not you.
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<div class="">Email validation is an area where many websites fall short as we found in our study on Website UA Readiness (nearing publication)</div>
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<div class="">The technologies behind these websites generally use a Regular Expression as their first line of defence against rubbish data. The issue is that most of these RegExs are overly restrictive.</div>
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<div class="">As an appendix to the Website review, we looked at some of the technologies behind the websites to see if there were common denominators for good and bad experiences.</div>
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<div class="">One RegEx has stood out as being simple and correct. I’d like the UASG to consider recommending this in our documentation. Toward that end, this thread is for discussion.</div>
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/^.+@(?:[^.]+\.)+(?:[^.]{2,})$</div>
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Regular expression check in Javascript. This accepts any Unicode characters, only insisting that the domain must have more than one label and the TLD is 2 characters or longer. </div>
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Your thoughts?</div>
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<div class="">Don Hollander
<div class="">Universal Acceptance Steering Group</div>
<div class="">Skype: don_hollander</div>
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