Great email app I've been using K9 mail for a long time & generally am happy with it. However I've had increased password issues in Gmail that require me to change my passwords frequently. K9 will not function properly if pw's are updated in the app-it continues to fetch mail  but sending mail fails after every pw update. The only solution I've found is to delete the application completely  reinstall  and setup the accounts all over again. This is becoming extremely tedious with all the pw updates I'm forced to make.
October 18 2016