Oh I see, no my phone is not routed, so that explains why they are blank
I have just checked my K9 settings and all three of the accounts are imap accounts so the emails are pushed to my phone, rather than syncing periodically with the server. My poll frequency is set to 'Never'.
I read here that push email shouldn't use much battery k9 Email check frequency settings help
With that in mind this drain issue is really baffling me, from the results do you think its still emails that are the issue or is there anything else that stands out?
I could try removing all my emails this evening and try the test again.