I tend to be a poor email filer. What I did was log into mailboxes.YOURDOMAINNAME.COM and set inbox housekeeping as follows:
Remove read messages when inbox reaches 250 messages.
Remove read messages from inbox older than 7 days.
Checked- Even expire new messages.
Checked- Archive expired messages in folder
Unchecked- Notify me when messages are expired (via a message in my inbox).
You also have to set a folder, which I change once a quarter manually. When I reply to emails I always BCC myself too, but that's just my preference.