I threw this together based of @ogiewon's Pushover driver for SendGrid. It's pretty basic but it gets the job done if you only need to send <100 messages/day and don't want to run your own SMTP server and don't have access to an app to do push notifications. You should also be able to email your SMS address with it, but I haven't tested that.
Requirements
This requires a SendGrid account; their free plan offers 100 emails/day
You will also have to verify an email address to “send as”; if you use a free mail provider (@gmail, @yahoo, etc), there may be delivery issues because of DMARC - this works better if you own your own domain, do your own DNS, and can make changes to your domain to ensure delivery. Luckily, Sengrid gives you a way to see all emails you've sent so you can determine if this will work before you really need it.
Create an API Key by going here and selecting CURL. Give it a name, create the key, then copy that key to the installation below. Leave this page open and go down to the installation then send a test. You should see it reflected in this page.
Installation
Easiest install method is via Hubitat Package Manager (HPM)
It says in the debug logs that the message was queued but I haven't seen it come through.
Check your SPAM folder.
Check the SendGrid Activity area to see if the notification was received.
I don't want to pay for SendGrid.
Neither do I. If you get it via GCP it is FREE for up to 12,000 emails a month.
Updates 26AUG2020: Added option for multiple recipients, option to BCC recipients, and option to send as high priority. 03SEP2020: Removed/replaced special chars & new lines in the message
That's an older version. Can you load up the driver and click import again? It should pull the latest version. Any idea if you know what notifications trigger that error? It might be a notification with something like quotes in it.
EDIT: New version out that escapes messages with newlines & special chars if you're having issues.
Just a shout out to @brianwilson for a stellar mail solution; works like a charm.
I tried the other mail solutions (HEMail & Sendmail) and they never worked.
Also tried the version where you run a local SMTP server on a Pi, and while that did work, I just didn't like it - I couldn't change the from e-mail address.
Oddball question: Upon RECEIVING mail successfully via SendGrid, in this example a gmail account, the FROM shows as "hubitat"; see image below
While this is NOT incorrect, I would like to show it with an uppercase "H", similar to
The limitation doesn't appear to be a) a web broser issue or b) g-mail in this case, but rather either the driver, or SendGrid itself.
Under 'Sender Address', save the field as Hubitat@yourdomain.com. Depending on how you've saved the sender address (uppercase or lowercase or mix) in the preference, gmail should show the 'From' username exactly the same way.
However, if you want to have a different 'First Name and Last Name' to the email address, then @brianwilson may have to make some changes in his driver.
Thanks for your replies.
I can confirm that the suggestion by @sujit works; by capitalizing the Sender Address it appears Capitalized in G-Mail. (can't speak for other e-mail apps)
Also added this to Hubitat Package Manager. You’ll need to run the match option if you’ve already got this driver installed, assuming you want it to be managed by HPM.