Apparently we have a misunderstanding here, so I will stress my point :
It will not work for outgoing emails (messages that exit the company network). This feature can only be envisioned inside the company.
As for terminating only a particular email, when I said include a flag field in the Memo form, I meant for that flag field to be the element that triggers the agent.
It does not mean that that field will automatically be filled, therefor you can perfectly make it a selectable option for the user.
To be honest, I see no use for this kind of functionality. What you want to do, in effect, simply reduces mailbox clutter. It will serve no purpose for email that leaves the company, so the only area where it can be useful is in the company.
When you are in the company, you have two different methods to avoid mailbox clutter :
1) Purge all mail older than (timeframe), except those flagged for keeping
2) Archive all mail older than (other timeframe)
Both of these actions can be implemented rather quickly, and will not change much of anything for the user. The main advantage is, they can be implemented at administrator level (ie the admin is the only one allowed to set the schedule), whereas the self-destruct is an operation that depends on the user.
More on the user : you cannot rely on users to be 100% efficient. That means that a mail that should be set to self-destruct can be sent without that option. Setting the option automatically will not change the problem, it will just reverse it.
The problem with this little detail is that the decision is to be made quickly (before sending the mail), and cannot be corrected once the mail is sent.
Whereas a purge option is something that allows users time to decide and get organized before the cutoff date is reached.
You can even modify the purge process to not take into account user mailbox's for users that are on holiday (a bit more programming, but can be done).
Pascal.