With international domain names almost everything is possible:

• Håkan.Söderström@malmö.se
• [email protected]
• 试@例子.测试.مثال.آزمایشی

If you want to do any tests you should first convert it to punycode.

Without punycode all you should do is to test that there:

• is at least one @
• is at least one character in the local part
• is at least one dot in the domain part
• is at least four characters in the domain (assuming that no-one has an address at the tld, that the tld is at least 2 chars)

Here is the code:

function isEmail(address) {
    var pos = address.lastIndexOf("@");
    return pos > 0 && (address.lastIndexOf(".") > pos) && (address.length - pos > 4);
}

With international domain names almost everything is possible:

• Håkan.Söderström@malmö.se
• [email protected]
• 试@例子.测试.مثال.آزمایشی

If you want to do any tests you should first convert it to punycode.

Without punycode all you should do is to test that there:

• is at least one @
• is at least one character in the local part
• is at least one dot in the domain part
• is at least four characters in the domain (assuming that no-one has an address at the tld, that the tld is at least 2 chars)

function isEmail(address) {
    var pos = address.lastIndexOf("@");
    return pos > 0 && (address.lastIndexOf(".") > pos) && (address.length - pos > 4);
}