Let's have a program that checks an email mailbox and then "processes" the messages contained there. (For this question it doesn't really matter what it actually does with the message). The program will run once per hour and can easily handle the volume of new messages and there is no penalty for processing a message twice. Let's say it will be using the IMAP protocol and can perform any of the standard functions that an email application can do.
What mechanism would you recommend for processing the email?
- Mark as read - the program marks a message as read after processing it.
- Unmodified mailbox - the program doesn't modify the mailbox at all.
- Something else - some other method I haven't thought of yet.