Tried to search through the past forum posts on how to set up email notifications. Found a ton of posts about it and a lot of different ways to do it dating back to 2018. There must be something simple by now but I'm not finding it.
I just want a way to send a notification to an email address. I don't care about SMS or text messages. I just need an app/device that supports SMTP where I enter my email address, credentials, port, etc.
I don't think there is any best way. Just whatever way that works for you.
For example, I use a webhook in IFTTT to do this from HE. I use IFTTT for a number of things also so end up paying their monthly subscription anyways.
I do things like when my alarm is triggered, IFTTT will email me, call me, text me and notify me that the bat cave has been breached. I also favorited their numbers/emails so even on DND I will get notified.
I'm not sure if they still have the free tier with 3 applets that you can utilize. But if you go with a subscription theres a bunch more you can do with it that is useful.
Agree that it is disappointing that there is no built-in option for this seemingly basic capability.
I use the community integration Sendmail to send myself email and text notifications:
By default it can send email notifications, and you can also use it to send yourself text messages by using your mobile carrier's email-to-text gateway (e.g., for Verizon, send an email to your phone number, e.g., 123-456-7890@vtext.com). It does require a compatible email address, usually the email address provided by your ISP (e.g., I use my Spectrum email address) will work w/Sendmail. Accounts on services like Gmail or Hotmail have additional security/requirements. If you have a compatible ISP email address I highly recommend Sendmail - especially because you can use it for both email and texting.
If mobile phone notifications would work for you, you can use the HE mobile app to receive those.
On mobile you can also use the Pushover service/mobile app - it's is a very simple, very cheap option, with a lot of features and controls. Easy to set up, one-time small payment, and very reliable. Down-side (like using the HE app) is it's a separate app that everyone who wants to get notifications needs to install on their phone.
There are other email options but they get more complex to set up, require configuring email support on a RPI, etc.
In addition to the resources that @danabw indicated, there is this excellent sendmail integration from @erktrek. I have been using it for a couple of years.