I mistakenly unsubscribed from the expiration notice. There are numerous certificates associated with this email address. Could you please remove the email address hostmaster@microtronics.com from the blacklist of http://mandrillapp.com?
I don't think they can do that. (One of the many shortcomings of their email notice system.)
The bottom of their expiration email documentation suggests the only resolution is to change the email address to another email address (or just wait a year). Many email providers allow for multiple email addresses to go to the same mailbox. It looks like you're using Microsoft's mail solution, though, which last I knew didn't have a "plus-addressing" type feature (though maybe they've added one since I last checked). You might be able to create an alias or email list with one member or something, to have a new email address like letsencryptnotices@ forward to your hostmaster@ one.
(Yeah, their mail system has a lot of room for improvement.)
Unfortunately, we usually cannot do this because of time and resource constraints; Iām sorry about that, and echo the recommendations earlier in this thread. We know the reminder email system has a lot of room for improvement.
Another option is to subscribe to a third-party monitoring service. An example that was set up by a member of this forum (but that is not affiliated with Let's Encrypt) is Let's Monitor. This is most useful if the certificates are being used on a publicly-accessible service (not an internal-only server).