Feature request: email notification

[lorenzo93]

Hi Greg,

I'm using CertWarden since 6 month now and it is running smoothly.

Congratulations for the project.

I was wondering if is there a way to receive email notifications if an auto renewal certificate got errors. For example if a cloudflare API key (I'm using their plugin via go-acme) got canceled or expired.
It would then be great also to be able to configure a list of domains and the system automatically checks if they have expired (or expiring) certificates in order to give you a head-up before the expiration date of the cert.

[rzech]

I just started experimenting with CertWarden in my homelab and was also wondering why there is no notification module. It would also be pretty helpful if a notification could be triggered by an API call. Let's say a client device with no mail server installed experiences an error on downloading / deploying a certificate/key. This device could then trigger an API call to CertWarden which then launches a notification.