Regex for email address without characters validation

Question

I need a regex that will check (if email is like a@b.cc:

email must have @ and . (must have both). I refer to the whole string that must contain @ and at least one dot.
1st word of email must have 1+ char
the domain name between @ and . must be 1+ char
TLD must be 2+ char

I made regex like .+@.+\. but it's not the one, I know. I am bad in regex as I use it so rarely.

Can anyone help me?

http://stackoverflow.com/questions/46155/validate-email-address-in-javascript?rq=1 — The One and Only ChemistryBlob, Sep 22 '16 at 14:27
@TheOneandOnlyChemistryBlob but this example is not checking if the domain name have 2+ chars — Matej, Sep 22 '16 at 14:29
@revo only the last word (a@a.com) should check for 2+ chars. PS. your does not work as well aa@aa.aa is not validated — sandalone, Sep 22 '16 at 14:31
Then you should clarify first requirement *email must have @ and .* Where `.` should be placed? — revo, Sep 22 '16 at 14:33
Again I should ask where `.` should appear? After `@` or before it? Are you referring to `.` in `.com` or in username? — revo, Sep 22 '16 at 14:35
As if you took words out of my mouth. @TheOneandOnlyChemistryBlob — revo, Sep 22 '16 at 14:38
@revo Like in .com. I don't care if an email is like this a@b.c.d.e.com. Only I want to make sure they entered a dot before the last word — sandalone, Sep 22 '16 at 14:42
Then your third and forth requirements conflict with each other. The name between `@` and `.` is the same as domain name. — revo, Sep 22 '16 at 14:43
@revo Only the last word in a string should be checked for 2+ chars. Others for 1+. Does this make sense? Just like in this email which is the minimum proper email `a@b.cc` — sandalone, Sep 22 '16 at 14:53
Is this one short enough? `^\S+@\S+\.\w{2,}$` . The `\S` stands for "non-whitespace", to avoid spaces, tabs, linefeeds. — LukStorms, Sep 22 '16 at 14:53
@sandalone so an email like `john.smith@domain.com` is invalid (because the username contains a dot)? — Bohemian, Sep 22 '16 at 14:54
@Bohemian It's validated with Luke's regex ;). But I also edited my question for sake of clearance. — sandalone, Sep 22 '16 at 14:56
If you be clear enough about requirements you will receive a well-formed answer sooner. Domain name != TLD. — revo, Sep 22 '16 at 14:58
@revo You are right. It's TLD and I called it domain name. IT's domain only actually. Sorry, my bad. — sandalone, Sep 22 '16 at 15:01

Billy Moon · Answer 1 · 2016-09-22T15:04:22.403

1

It's not clear if you are matching an email in the middle of a paragraph of text, or matching an already extracted string. I am assuming the latter, and anchoring the match to start and end of line...

/^.+@.+\.[^.]{2,}$/

p.s. using regex to validate emails is complex: http://www.regular-expressions.info/email.html

edited Sep 22 '16 at 15:04

answered Sep 22 '16 at 15:01

Billy Moon

57,113
24
136
237

Just regular email a user gives during signup. Local validation. – sandalone Sep 22 '16 at 15:02
your regex is basically useless. it matches `@@@@@@@.@@` for example – Bohemian Sep 22 '16 at 15:18
@Bohemian yep - question does not specify that as being a problem. As indicated in footer note, email validation is complex. I remember using angular js email validation in Ireland, and it does not allow `'` in a name, so that was a good chunk of people's emails not working. The more situations you account for, the more complex the regex becomes until it's so complex you want to go back to something simple again. Also, what is not valid or infeasible email today, might become valid tomorrow. There is a section about trade-offs in the link I sent. – Billy Moon Sep 22 '16 at 15:22
@Bohemian I'd argue that any validation more complex than this is basically useless. It wouldn't be if it wasn't for the fact that seemingly everyone gets it wrong. As a matter of fact, even this one will fail on a legitimate email like "bob@localdomain" since it expects a TLD but I'd call that acceptable because in the vast majority of cases, it's external emails that one works with. – VLAZ Sep 22 '16 at 15:39
@vlaz what about bobby@154.233.153.1 which is also ok email I think, or perhaps IPv6? – Billy Moon Sep 22 '16 at 15:41
@BillyMoon yep, that's also going to be rejected but...you know - it's not _really_ that common to use those. Same with the domains without a TLD. But the my ideal validation `.+@.+`. That should be enough to catch most gross mistakes. Then a soft validation can be done for the domain part - `.+\..+` (or `[^.]+\.[^.]+) to check if it has a TLD and if not, just mention it to the user "Are you sure that is correct and you want to use this email?". But that's about as hard I'd like to go on email validation via regex. Just send an email to confirm it afterwards. – VLAZ Sep 22 '16 at 15:49
@vlaz I agree with `.+@.+` and the key point that the validation should be used to inform the user, and not to prevent form submission. – Billy Moon Sep 22 '16 at 15:56

Regex for email address without characters validation

1 Answers1