Cannot correctly validate cyrillic (or any other UTF-8) characters in local part

[weierophinney]

Here is the usage of the validator in the form:

[
    "name" => "email",
    "required" => false,
    "validators" => [
        [
            "name" => "EmailAddress"
        ]
    ]
]

The problem occurs when the user enters an email with UTF-8 characters in the local part.
Here is an example: тест@example.com

While debugging, Zend\Validator\EmailAddress::validateLocalPart() returns (boolean) true, thus causing the input to be valid (but it isn't).

Afterwards, sending an e-mail is impossible, because тест@example.com gets into the e-mail headers and they become invalid.

I have investigated the problem and it turns out that $this->idnToAscii($this->localPart) in the Zend\Validator\EmailAddress::validateLocalPart() method is causing the problem. It converts all UTF-8 characters to ASCII and makes the preg_match. It returns true and voila - wrong validation.

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Originally posted by @thexpand at zendframework/zend-validator#119

[weierophinney]

Sorry, I'm not 100% clear on the problem: is it that тест@example.com is being accepted by the validator when you think it shouldn't? Or is the problem in sending an email to that validated address?("Afterwards, sending an e-mail is impossible...")

If it's the former, UTF-8 characters above U+007F are technically allowed in the email address local part (RFC 6531) though I don't know anything about specific implementations and what they do or don't accept.

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Originally posted by @adamlundrigan at zendframework/zend-validator#119 (comment)

[weierophinney]

I thought that the validator should not accept UTF-8 characters in the local part at all.
Maybe I was wrong.

However, there is a problem afterwards when sending the e-mail.
The headers seems to be invalid.
Because of the invalid headers I thought that the validator is not working right.

Any ideas?

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Originally posted by @thexpand at zendframework/zend-validator#119 (comment)