Send Later is an application that lets you send emails, scheduled basis. Choosing the day and the time at which you want to receive the message, the person you want, without having to confirm the day of shipment.
You only have to configure the mail, on the Date / Time button youll find within the program option. You can set up multiple email accounts.
If you do not know the SMTP, your email account you can see some examples in the "?" or find easily on Google: SMTP "type of account".
DIFFERENCE REGARDING PAYMENT:
All emails sent bear the signature "Sent by SEND LATER" so the recipient will know that the mail has been scheduled ....
If that is not inconvenient at the moment is not worth you spend € 1;)