Hi,
There're rules to delete emails you receive, but unfortunately, there's no such rule to auto-delete sent mail within sent items folder.
However, we can use a script rule to achieve the goal. The following macro will set the message to expire in 1 day. You can use .5 to expire the message after 12 hours.
If you use conditions in the rule to filter the messages, you can remove the IfThen and End If lines from the code.
Sub SetExpire(Item As Outlook.MailItem) If Left(LCase(Item.Subject), 7) = "weather" Then Item.ExpiryTime = Now + 1 Item.Save End If End Sub
Reference: http://www.slipstick.com/outlook/rules/create-rule-to-expire-mail-after-a-number-of-days/
Since we are not the best resource for coding, if you need further assistance regarding the coding portion, I'd recommend you post a new question in the Outlook for Developers forum:
https://social.msdn.microsoft.com/Forums/office/en-US/home?forum=outlookdev
The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.
Steve Fan
TechNet Community Support