@riahc3
Thank you for posting in this 16 months old thread.
BTW:
Kostya's remark "(and as far as I know, there is no such feature in Thunderbird or Outlook on "big" computers, either)" was merely a presumption - but not an assertion.
So, what is your intention for such an offensive post against the developer
In addition to that: AquaMail is a really, really "small" app, designed for a mobile device, not a powerful PC / Mac desktop application like Thunderbird or Outlook.
It would be interesting, whether 'Outlook for Android' (the app - not the desktop application) offers this functionalityb I'm not aware of this.