I’m on android, but i think that most things should work the same on ios.
There are multiple reasons for empty/extra log-files to appear.. Maybe you toggled logging on/off while messing with app and ~forget, changed settings while logging was enabled, mooshimeter crashed and rebooted (it should be able to continue on same file) etc.
You can delete logs via app, you just need to view them first for some reason. While you are transferring single file, there is a trashcan icon. Its easier to delete tens of files with pc though.
Its not that often that i need to send my raw logs by email, but as i tried, i got to see the file just fine as attachment on gmail-app*. Maybe your email-client does not like to send stuff back to itself? What if you save that mail as a draft? Should be able to open it on another device, if email is the way you want to go.. I “share” my logs to google-drive if further processing on another device is needed.
* – on gmail, i did not have to write whole address, after couple letters it offers right address, like always. What options does ios offer for sharing, as android gives me million choices for how to share things, not just one email-client?