Email address validator

Is this email address written correctly?

Every list of email addresses has some bad entries: a missing @, a space, a comma typed instead of a full stop, or a domain that should read gmail.com but says gmial.com. They cause bounced messages, wasted effort and damage to the reputation of your sending address. Checking them before you send is quick with this tool, which examines the format of one address or a whole list at once.

What is checked

• There is exactly one @, with something before it and after it.
• The part before the @ is not longer than 64 characters, uses allowed characters and has no leading, trailing or doubled dots.
• The domain has at least one dot, each label is 1 to 63 characters and does not start or end with a hyphen, and the ending, such as .com, is made of letters.
• The whole address is not longer than 254 characters and has no spaces.

Helpful notes

Beyond right and wrong, the tool adds notes that a plain check would not. It suggests the correct domain for common typos, such as gmial.com or hotmial.com. It warns when the domain belongs to a known disposable email service, whose addresses vanish after a short time. It points out role addresses such as info@ or admin@, which belong to a team rather than a person, and it notes addresses with a plus tag, which are valid but rejected by some forms.

What a format check cannot tell you

An address that is correctly written may still not exist. A mailbox can be full, closed or never have existed, and a domain can be unregistered or not accept mail. Finding out requires contacting the mail server, which a browser tool cannot do and which would mean sending the addresses to a third party. To be sure an address works, you need to send to it and see, or use a confirmation email in your sign-up process.

What it does not do

The check follows the practical rules that most services apply, not every exotic form allowed by the standard, such as quoted local parts or address literals. Nothing you paste leaves your browser. To pull addresses out of a block of text first, use the email extractor.