Regex should accept multiple dots but don't

Question

I want to accept mail formats like these :

"x@x.com"
"x.x@x.com"
"x.x@x.com"
"x.x.x@x.com"
"x@x.x.x.com"
"x@x.x.com"
"etc..."

How can I modify this regex to accept dots inside emails?

@"^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$"

thank you.

Replace `(\w){2,3}` with `\w{1,3}` or `([\w\-]+)` with `([\w.-]+)` — Wiktor Stribiżew, Apr 18 '17 at 07:29
Don't work :/ mails like na.va.waterloo@deal.rena.com are not accepted. Can you post the entire regex? maybe I'm wrong with ur modifications. — amin89, Apr 18 '17 at 07:37
[`na.va.waterloo@deal.rena.com` is matched](https://regex101.com/r/1nKgb5/1) — Wiktor Stribiżew, Apr 18 '17 at 07:40
thank you a lot. Actually, I have onother little problem with 5 of my list of e-mails. An email like this don't match : dom.d@inter.city .. no dot at the end. How can I modify your regex to accept it? — amin89, Apr 18 '17 at 07:45
BTW, see [Regex Email validation](http://stackoverflow.com/questions/5342375/regex-email-validation) — Wiktor Stribiżew, Apr 18 '17 at 07:47
thank you :) I don't master regex so you have done a lot for me ;) — amin89, Apr 18 '17 at 07:50
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/141948/discussion-between-amin89-and-wiktor-stribizew). — amin89, Apr 18 '17 at 07:52
Use the other option - [`^([\w.-]+)@([\w-]+)((?:\.\w{1,4})+)$`](https://regex101.com/r/1nKgb5/2) — Wiktor Stribiżew, Apr 18 '17 at 07:53
78 emails don't match with the last regex ^^" Damn I should learn how all this work .. — amin89, Apr 18 '17 at 07:58
Just use [this approach](http://stackoverflow.com/a/5342460/3832970). Do not bother with regex. — Wiktor Stribiżew, Apr 18 '17 at 07:59
BTW, are you aware that TLD (last part of the domain name) can be longer than 4 characters (`.london` or `.travel`) — strah, Apr 18 '17 at 08:41
The last regex I can share is [`^([\w.-]+)@([\w.-]+)(\.\w+)$`](https://regex101.com/r/1nKgb5/3) - but now you understand how fragile the regex approach is. — Wiktor Stribiżew, Apr 18 '17 at 08:47
Probably the only one way to know, is an email valid or not is to send the email to it — VMAtm, Apr 18 '17 at 11:14

score 1 · Accepted Answer · edited May 23 '17 at 12:17

To answer your question: when your after-@ part contains more than 1 dot, the one-char parts between the dots cannot be matched due to the {2,3} limiting quantifier minimum threshold. It requires at least 2 chars in between the dots.

You could fix it with ^([\w.-]+)@([\w.-]+)(\.\w+)$ where all the dot parts but the last one in the domain part would appear in Group 2 and the last one will be in Group 3.

The best approach to validate an e-mail in .NET is the one described here.

Regex should accept multiple dots but don't

1 Answers1