Just for completeness, here you have another RFC compliant regex. The official standard is known as RFC It describes the syntax that valid email addresses must adhere to.
You can but you shouldn't — read on implement it with this regular expression:. We get a more practical implementation of RFC if we omit the syntax using double quotes and square brackets. It will still match A further change you could make is to allow any two-letter country code top level domain, and only specific generic top level domains. This regex filters dummy email addresses like asdf adsf. You will need to update it as new top-level domains are added.
So even when following official standards, there are still trade-offs to be made. Don't blindly copy regular expressions from online libraries or discussion forums. Always test them on your own data and with your own applications. I've slightly modified Jaymon's answer for people who want really simple validation in the form of:.
Other than that it's all just guesses.
A valid e-mail address is a string that matches the email production of the following ABNF, the character set for which is Unicode. This requirement is a willful violation of RFCwhich defines a syntax for e-mail addresses that is simultaneously too strict before the " " charactertoo vague after the " " characterand too lax allowing comments, whitespace characters, and quoted strings in manners unfamiliar to most users to be of practical use here.
A good practice is to validate your data on the client, but double-check the validation on the server. With this in mind, you can simply check whether a string looks like a valid email address on the client and perform the strict check on the server. Last should be before last.
There should be something the email username before the last. There should be no in the address. Even if appears as the last character in email username, it has to be quoted so " would be between that and the last in the address.
There should be at least three characters before the last dot, for example a b. There should be enough characters after the last dot to form a two-character domain. I'm not sure if the brackets are necessary. Don't bother with anything more complicated.
It's too complicated and would not cover all the cases. You can refine it. For instance, 'aaa ' is valid. But overall you get the gist.
And don't get carried away This is how node-validator does it:. The only real way to get it correct would be to send a test email to the account.
That said, there are a few basic checks that can help make sure that you're getting something reasonable. Second, check to make sure that a period comes after the sign, and make sure that there are characters between the s and periods.
Almost all answers to this questions suggest using Regex to validate emails addresses. I think Regex is only good for a rudimentary validation. It seems that the checking validation of email addresses is actually two separate problems:. A list of all valid TLDs can be found here. For example, although the address example example.
My knowledge of regular expressions is not that good. That's why I check the general syntax with a simple regular expression first and check more specific options with other functions afterwards. This may not be not the best technical solution, but this way I'm way more flexible and faster. The most common errors I've come across are spaces especially at the beginning and end and occasionally a double dot.
The regular expression provided by Microsoft within ASP. Thank you for your interest in this question.