checkmail

README

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

Install the Checkmail package

go get github.com/badoux/checkmail

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.

Documentation

Index

• Variables
• func DialTimeout(addr string, timeout time.Duration) (*smtp.Client, error)
• func ValidateFormat(email string) error
• func ValidateHost(email string) error
• func ValidateHostAndUser(serverHostName, serverMailAddress, email string) error
• func ValidateMX(email string) error
• type SmtpError
  • func NewSmtpError(err error) SmtpError
  • func (e SmtpError) Code() string
  • func (e SmtpError) Error() string

Variables

var (
	ErrBadFormat        = errors.New("invalid format")
	ErrUnresolvableHost = errors.New("unresolvable host")
)

Functions

func DialTimeout

func DialTimeout(addr string, timeout time.Duration) (*smtp.Client, error)

DialTimeout returns a new Client connected to an SMTP server at addr. The addr must include a port, as in "mail.example.com:smtp".

func ValidateFormat

func ValidateFormat(email string) error

func ValidateHost

func ValidateHost(email string) error

ValidateHost validate mail host.

func ValidateHostAndUser

func ValidateHostAndUser(serverHostName, serverMailAddress, email string) error

ValidateHostAndUser validate mail host and user. If host is valid, requires valid SMTP [1] serverHostName and serverMailAddress to reverse validation for prevent SPAN and BOTS. [1] https://mxtoolbox.com/SuperTool.aspx

func ValidateMX

func ValidateMX(email string) error

ValidateMX validate if MX record exists for a domain.

Types

type SmtpError

type SmtpError struct {
	Err error
}

func NewSmtpError

func NewSmtpError(err error) SmtpError

func (SmtpError) Code

func (e SmtpError) Code() string

func (SmtpError) Error

func (e SmtpError) Error() string