✉️ Email Address Validator (RFC 5322)

Check a single email address against practical RFC 5322 syntax rules and see a breakdown of its local part and domain. This checks syntax only — it does not verify the address exists.

Email Address

The checks it runs

This is a syntax test in your browser - no DNS query, no MX lookup, no connection to the mail server. The address is split at the last @, then five rules are applied and every failure is listed:

total length   <= 254 characters   (RFC 5321)
local part     1-64 characters
domain part    non-empty, contains at least one dot
pattern        local@label.label, labels 1-63 chars, no leading or trailing hyphen

So user.name+tag@example.co.uk passes: a 14-character local part, a domain of three valid labels. user@localhost fails on the missing dot, and an address of 260 characters fails on length even if it is otherwise well formed.

What "valid" does and does not mean

Plus addressing is legal. So are !#$%&'*+/=?^_`{|}~ in the local part. Sites that reject + are being stricter than the standard, not safer.
The pattern is the practical approximation, not the full RFC 5322 grammar. It does not accept quoted local parts such as "john doe"@example.com or IP-literal domains such as user@[192.0.2.1], both of which are technically legal and almost never useful.
It is lenient about dots. A local part with a leading, trailing or doubled dot still matches the pattern here, although a strict reading of the standard disallows it and some mail servers will refuse it.

A "Valid" result says the string is shaped like an address. It says nothing about whether the mailbox exists, accepts mail, or belongs to the person who typed it. Only a confirmation email settles that.

Frequently asked questions

Is user+tag@gmail.com a valid email address?

Yes. The plus sign is an ordinary character in the local part, and Gmail routes anything after it to the same inbox. This validator accepts it.

What is the maximum length of an email address?

254 characters overall, with at most 64 before the @. Those come from RFC 5321's limits on the SMTP path rather than from the address grammar itself, and this tool flags both.

Does this tell me if the address is real?

No. It never leaves your browser, so it cannot know whether the domain resolves or the mailbox accepts mail. Treat it as a first filter that catches typos and malformed input.