Gave up on K9
I used K9 for a long time, thinking it was working ok. My battery would last all day and still had 30% remaining when I went to bed. All of the sudden I started getting severe battery drain and traced it to K9. (I had not changed any K9 settings.) I don't know if there was an update that caused the problem or just "stuff happens". All of the sudden my battery started to drain after less than 12 hours. I removed K9 and installed Aqua. I now get over 50 hours out of my battery. That's twice what I was getting when I thought K9 was working well and four times the "post problem" K9. I guess there was always a problem to some extent and it suddenly became severe.
This is the first I've posted on an Android forum and I hope it helps someone. Without forums such as this my phone would not be the productivity tool it has become.
Keep up the posts!!