Email Validation: Check Address Format & MX Records
Validate email address format and check MX records instantly. Verify if an email domain has a mail server.
Get the tool mentioned in this guide in the desktop app:Email Validator
Why validate email addresses?
Email validation catches typos and invalid formats before sending. There are two levels:
1. Syntax validation — Check if the email matches RFC 5322 format ([email protected]).
2. Domain validation — Check if the domain has mail servers (MX records).
Syntax validation is fast and catches obvious typos. MX record checking confirms a domain actually receives email, but requires a DNS lookup and adds latency.
Email address format (RFC 5322)
A valid email has:
- A local part (username) — alphanumeric and special characters (. _ - + etc.)
- An @ symbol
- A domain name — must have at least one dot (example.com).
- A top-level domain — at least 2 characters (com, org, uk, etc.)
Common invalid patterns: - Missing @ or domain. - Double @ signs. - Spaces or special characters in the local part (unless quoted). - Domain with no dots or invalid TLD.
// Valid emails
[email protected]
[email protected]
[email protected]
// Invalid emails
alice@example (no TLD)
alice.example.com (no @ sign)
alice@@example.com (double @)
[email protected] (empty local part)MX record checking
An MX (Mail Exchange) record tells the internet how to deliver email to a domain. Every legitimate email domain should have at least one MX record pointing to a mail server.
MyDevTools Email Validator checks if a domain has MX records, confirming it actually accepts email. This is more thorough than syntax checking but requires a DNS lookup from the server.
When to validate and when not to
Always validate: - On signup forms (catch typos before account creation). - Before sending transactional emails (confirmation, reset links).
Consider MX checking: - On critical workflows (newsletter signup, account recovery). - Not needed for every form — syntax validation alone is often sufficient.
Frequently asked questions
What characters are valid in the local part of an email?
Alphanumerics (a-z, 0-9), dots (.), dashes (-), underscores (_), plus (+). Spaces and some special chars require quoting.
Can an email without an MX record still receive mail?
Technically no — without an MX record, mail servers do not know where to send email. Most legitimate domains have MX records.
Is email validation 100% accurate?
No tool is 100% accurate. Syntax validation catches obvious errors. MX checking confirms a domain can receive mail but does not validate the specific user account.