[UA-discuss] [UA-EAI] Regular Expression To Validate EAI Addresses

[John Levine]

In article <14D6CA6C-2F5F-4FAB-8602-41B700DB727E at viagenie.ca>,
Marc Blanchet <marc.blanchet at viagenie.ca> wrote:
>The recommendation I made during the Java tutorial on UA is as follows:
>- use a simple regex to throw out the basic errors (example: an (EAI 
>email address must have a « @ «  and at least one « . » on the 
>right side; you can enhance this a bit, but if you go too much, then you 
>start getting into trouble)
>- use a library for verifying IDNA.
>- there is not that much one can do on the left side of an EAI email 
>address. maybe just verifying it is a valid UTF-8 string.
>
>John Levine also wrote similarly in a previous email in this thread.

You can do a little more validation of the mailbox to be sure it follows
the syntax rules, e.g., doesn't have two unquoted dots in a row.  For practical
purposes I would also exclude % and ! which used to be (ab)used for source
routing and are likely to fail.

-- 
Regards,
John Levine, johnl at taugh.com, Primary Perpetrator of "The Internet for Dummies",
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