6 min read
2026-01-28
Invalid email addresses lead to undelivered messages, damaged sender reputation, and database errors.
An email consists of two parts separated by the @ symbol:
| Part | Allowed Characters |
|---|---|
| Local | Latin letters, digits, dots, hyphens, underscores |
| Domain | Latin letters, digits, hyphens, dots |
**Syntax** — compliance with RFC 5322 format
**Length** — no more than 254 characters total
**Domain** — correctness of the domain name
**Special characters** — proper use of dots and special characters
Spaces in the address
Two consecutive dots in the local part
A dot at the beginning or end of the local part
Cyrillic characters in the address (not all servers support them)
Missing top-level domain
Check addresses with the Email Validator.
See also: URL Validator, Phone Validator