Hello,
at the moment there is only one automated empty trash option - after one month.
It would be nice to add a second possibility - after one week.
It is not a life saving feature but it would be nice to have it. 
Best
P.S. in iOS and macOS this option exists but it is not overwriting Runbox own one month setting.
Hello. Yes, options to change the period after which mail is emptied might be useful to some people. Feel free to suggest it here: https://github.com/runbox/runbox7/issues
iOS and macOS can’t overwrite the Runbox option because the option on our servers is unaware of any setting in those email programs and mail is deleted by a script that is entirely different to the method used by an email app.
I don’t have the desire to signup with Github. Forget my request!
Thank you Dave!
Best