notification

type Email struct {
	From      string   `json:"from"`
	To        []string `json:"to"`
	CC        []string `json:"cc"`
	BCC       []string `json:"bcc"`
	ReplyTo   string   `json:"reply-to"`
	Subject   string   `json:"subject"`
	Body      string   `json:"body"`
	HTML      string   `json:"html"`
	CheckSent bool     `json:"check-sent"`
}

type Error struct {
	// Message is a text that describes an error.
	Message string `json:"message"`
	// Code is a number that identifies error.
	// It allows error identification when serialization is involved.
	Code int `json:"code"`
}

type Service interface {
	// SendEmail sends an e-mail message and returns it's ID.
	SendEmail(email Email) (id string, err error)
	// IsEmailOptedOut returns true or false if e-mail address
	// is marked not to send any e-mail messages to.
	IsEmailOptedOut(email string) (yes bool, err error)
	// OptOutEmail marks an e-mail address not to send any e-mail messages to.
	OptOutEmail(email string) (err error)
	// RemoveOptedOutEmail removes an opt-out mark previosulu set by
	// OptOutEmail.
	RemoveOptedOutEmail(email string) (err error)
}