Create EmailStatus type

[elimisteve]

Should track the status of sending a particular email so we know which ones succeeded and which ones failed. Should include ForeignKey to the email whose status the given EmailStatus "object" is tracking.

[elimisteve]

type EmailStatus struct {
    Email *Email // Not sure which is better
    EmailId string // Not sure which is better
    Status SentStatus // This helps reduce type errors and will remind us to use pre-defined constants
    ...
}

[elimisteve]

What should SentStatus be? Ideas:

type SentStatus string // This is called a "type alias"

const (
    QUEUED SentStatus = "queued"
    SENDING SentStatus = "sending"
    SUCCESS SentStatus = "success"
    FAILED SentStatus = "failed"
)

Another idea:

type SentStatus uint // Another type alias, this time with the `int` type

const (
    QUEUED SentStatus = iota
    SENDING
    SUCCESS
    FAILED
)

See http://golang.org/ref/spec#Iota and the paragraph right before it.

[elimisteve]

Another good iota example: http://golang.org/doc/effective_go.html#constants