Outlook Add-Ons for Scheduling Emails
SendLater - Outlook Email Scheduling Add-On
SendLater makes it easy to schedule a message to be delivered at a later date in Outlook, and even recurrently on a schedule or when an attached file has changed locally.
Email Scheduler - Outlook Email Scheduling Add-On
Email Scheduler lets you send emails and files in the future once or periodically using a very flexible schedules.