Unwanted notifications when drive is not connected

[Cosimo Cecchi]

I have deja-dup set up to backup my laptop to an external USB drive; deja-dup is now triggering a notification that the external drive is not connected several times a day, after booting the computer and when resuming from suspend.
The text says that the backup has been delayed until the external drive is connected.

I think it's okay to have a notification to remind me to connect the drive every once in a while (OSX's Time Machine does that for instance), but it shouldn't happen more often than once every two or three days, and have a description to that extent.

This is with Fedora 20, deja-dup-27.3.1 and gnome-shell 3.12.