validate email addresses using a regex.

Question

I am trying to validate email addresses using a regex. This is what I have now ^([\w-.]+)@([\w-]+).(aero|asia|be|biz|com.ar|co.in|co.jp|co.kr|co.sg|com|com.ar|com.mx|com.sg|com.ph|co.uk|coop|de|edu|fr|gov|in|info|jobs|mil|mobi|museum|name|net|net.mx|org|ru)*$ I found many solutions using non-capturing groups but did not know why. Also can you tell me if this is the correct regex and also if there are any valid emails which are not being validated correctly and vice-versa

Answer 1

Don’t bother, there are many ways to validate an email address. Ever since there are internationalized domain names, there’s no point in listing TLDs. On the other hand, if you want to limit your acceptance to only a selection of domains, you’re on the right track. Regarding your regex:

• You have to escape dots so they become literals: . matches almost anything, \. matches “.”
• In the domain part, you use [\w-] (without dot) which won’t work for “@mail.example.com”.
• You probably should take a look at the duplicate answer.
• This article shows you a monstrous, yet RFC 5322 compliant regular expression, but also tells you not to use it.

I like this one: /^.+@.+\...+$/ It tests for anything, an at sign, any number of anything, a dot, anything, and any number of anything. This will suffice to check the general format of an entered email address. In all likelihood, users will make typing errors that are impossible to prevent, like typing john@hotmil.com. He won’t get your mail, but you successfully validated his address format.

In response to your comment: if you use a non-capturing group by using (?:…) instead of (…), the match won’t be captured. For instance, all email addresses have an at sign, you don’t need to capture it. Hence, (john)(?:@)(example\.com) will provide the name and the server, not the at sign. Non-capturing groups are a regex possibility, they have nothing to do with email validation.