As we mentioned, Archive automatically moves messages according to age. That is, messages move to an archive folder when they achieve "maturity" as determined by the setting you specify in the AutoArchive dialog box.
Maturity is based on how long a message sits around without your touching it. That is, maturity is based on a message's last modified date.
The following actions change the modified date (and time) of a message and will therefore affect when that message is archived:
- Replying to all
- Editing and saving
If a message isn't archived and you think it should have been, it's probably because you changed its modified date by forwarding or replying to it (or by doing one of the other actions).