type Mailer struct {
// contains filtered or unexported fields
}
Mailer type contains a mail.Dialer instance (used to connect to a
SMTP server) and the sender information for your emails (the name and address you
want the email to be from, such as "Alice Smith <alice@example.com>").
func (m Mailer) Send(recipient, templateFile string, data interface{}) error
Send() takes the recipient email address
as the first parameter, the name of the file containing the templates, and any
dynamic data for the templates as an interface{} parameter.