checkmail

Golang package for email validation.

• Format (simple regexp, see: https://www.w3.org/TR/html5/forms.html#valid-e-mail-address and https://davidcel.is/posts/stop-validating-email-addresses-with-regex/)
• Valid domain
• Valid user: verify if the user and mailbox really exist

Usage

1. Format

func main() {
    err := checkmail.ValidateFormat("ç$€§/az@gmail.com")
    if err != nil {
        fmt.Println(err)
    }
}

output: invalid format

2. Domain

func main() {
    err := checkmail.ValidateHost("email@x-unkown-domain.com")
    if err != nil {
        fmt.Println(err)
    }
}

output: unresolvable host

3. Host and User

If host is valid, requires valid SMTP serverHostName (see to online validator) and serverMailAddress to reverse validation for prevent SPAN and BOTS.

func main() {
    var (
        serverHostName    = "smtp.myserver.com" // set your SMTP server here
        serverMailAddress = "validuser@myserver.com"  // set your valid mail address here
    )
    err := checkmail.ValidateHostAndUser(serverHostName, serverMailAddress, "unknown-user-129083726@gmail.com")
    if smtpErr, ok := err.(checkmail.SmtpError); ok && err != nil {
        fmt.Printf("Code: %s, Msg: %s", smtpErr.Code(), smtpErr)
    }
}

output: Code: 550, Msg: 550 5.1.1 The email account that you tried to reach does not exist.

License

Checkmail is licensed under the MIT License.