Outbox is a very useful feature in Mail, by which you can hold your email for a predefined duration of time in minutes, before you actually send out the email. This gives you a safe buffer in which you can make some minor changes to the mail you just sent.
The sending interval or the Outbox interval is the time duration in minutes, during which time, the mail will be retained in your Outbox before actually sending.
Sometimes the messages scheduled to send may remain unsent due to some errors. In such case, the Outbox will display the error messages with a red warning icon.To send them, open the Outbox, select those messages and click Send Immediately. If the ...