Mailbox Expiration Tracking

[ObviousInRetrospect]

Is your feature request related to a problem? Please describe.
SavedInstances is great for tracking to-do's across too many alts. Mailboxes get stale and mail gets deleted or returned - keeping track of what needs cleaning is a pain. I replaced a spreadsheet with SavedInstances - the primary thing I can't figure out how to track is expiring mail dates.

Describe the solution you'd like
Add a row for mailbox first expiration/return. Fine if it

Describe alternatives you've considered
Altoholic has this functionality but its interface is far worse and you have to hover over each line to see the date. It is also very buggy

Additional context
Happy to submit separate requests but a few other missing things:

• Great Vault not yet emptied check
• Had to manually add Show Your Mettle weekly quest (doing so is easy enough but it seems like a good candidate for default)