Send emails/notifications to users before the expiration date is reached.

[tcitworld]

Like #29 but before the actual expiration to warn them.

Needs a new input to pick the number of days after which user should receive a warning email.

[heri410]

That would be very usfull.

[nickvergessen]

@tcitworld you self-assigned 1.5y ago. Still plan to implement this?

[tcitworld]

I still need it in the foreseeable future, but feel free to assign yourself.

[tcitworld]

I didn't mean to close the issue, sorry about that.

[tcitworld]

@nickvergessen This can be closed now, right?

[nickvergessen]

Yes, thanks.

[nickvergessen]

Added the UI task to #118