How many @ symbol can be in an email address?

Question

Is there any rule for having a specified amount of @ symbol in any email id. Just come to my mind if we\'re to check if an email id is valid or not using PHP.

Answer 1

There is no specific limit on @ characters.

"very.(),:;<>[]\".VERY.\"very@\\ \"very\".unusual"@strange.example.com is a valid address.

See also, the Wikipedia page on the subject.