How to write regular expression to match free email accounts?

问题

I'm trying to write a regular expression that checks if an email form field contains a free email address, with no luck.

Essentially I need to check if the email contains: hotmail, yahoo, gmail etc in the email field.

回答1:

regex would be sth like:

[a-zA-Z0-9_\.+]+@(gmail|yahoo|hotmail)(\.[a-z]{2,3}){1,2}

you can add all the other domains you want... does it help you?

回答2:

/\@(hotmail|yahoo|gmail)\.com/

回答3:

Have you tried a big ol' disjunction?

i.e.

yahoo\.com|googlemail\.com|blah\.net

Pros: Easy to build, easy to read, explicit.

Cons: Maybe not the most efficient mechanism.

来源：https://stackoverflow.com/questions/2318214/how-to-write-regular-expression-to-match-free-email-accounts