- mu4e-main.el: mu4e-update-mail-show-window retrieves mail / updates
database, show output in split window (actual work is done by...:)
- mu4e.el: mu4e-update-mail retrieves mail, updates database,
asynchronously. Optionally, show output in a buffer
when `mu4e-update-interval' is non-nil and some integer, it calls
mu4e-update-mail every so many seconds.
- mu4e.texi: document this
- TODO: updated