Gmail Address with Canonical Normalization Regex for Go

What this pattern does

This page provides a well-structured, multi-part regular expression for matching gmail address with canonical normalization, ported and verified for Go. Identity and credential patterns need both correctness and safety, since they're frequent targets for adversarial input. The snippet below is ready to drop into your Go project — whether you're validating in a Gin handler, a gRPC service, or a command-line tool.

Go Implementation

// Gmail Address with Canonical Normalization
// ReDoS-safe | RegexVault — Identity & PII > Email Address

package validation

import "regexp"

var gmailAddressWithCanonicalNormalizationRe = regexp.MustCompile(`^[a-zA-Z0-9]+(\.[a-zA-Z0-9]+)*(?:\+[^@]*)?@(gmail\.com|googlemail\.com)$`)

func ValidateGmailAddressWithCanonicalNormalization(s string) bool {
    return gmailAddressWithCanonicalNormalizationRe.MatchString(s)
}

// Example
// fmt.Println(ValidateGmailAddressWithCanonicalNormalization("user@gmail.com")) // true

Test Cases

When to use this pattern

This pattern is drawn from the Identity & PII > Email Address category and carries a ReDoS-safe certification. That matters for Go developers because Go's RE2 engine is inherently safe from catastrophic backtracking, but this pattern has been additionally verified for correctness. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

Gmail canonicalization: strip dots from local part, strip everything from + to @ inclusive, lowercase. u.s.e.r+tag@gmail.com and user@gmail.com deliver to the same inbox. Also, googlemail.com is an alias for gmail.com.