Mail rules does not seem to let you operate on a specific mailbox.
Mine are set at one month, and it seems to work.This info via Google doesn't work?
To set how long deleted emails stay in the Trash mailbox.
You should then see the options to remove deleted messages:
- Go to Settings
> Passwords & Accounts.![]()
- Tap your iCloud email account > Tap iCloud > tap Mail (at the very bottom)> then tap Advanced.
- In the Advanced settings, tap Remove, then select a time interval.
Never
After one day
After one week
After one month