Sieve, as a language/protocol, must be held to stricter standards than
any single implementation.
I gave an example, where I know that expiry on delivery would be almost
for free, to show that there are alternatives to a regular cleanup job.
That's why I would allow both.
If sieve makes the promise that a a mailbox should contain only the past
seven days' mail, users might reasonably rely on that.
If Sieve makes that promise, yes, but that's not what I was talking about.
I didn't talk about a privacy feature, either, but about a convenience
feature, and that's why I don't have a "privacy/security issue".
The feature I described is: Hey, MDA, you can throw messages in this
folder away after n days. A great thing for subscribed newsletters.
FWIW, I also don't like the idea of sieve managing folder properties.
That seems to be out of scope for sieve.
That's a point I can understand. If Sieve focuses only on messages,
then manipulating persistent folder attributes would be simply out
of scope. Does it focus strictly on messages, not folders, despite
folders containing messages?
If so, how about message attributes to allow expiration to happen?
Michael