Once once upon a time I had my cameras and IoT things emailing out through SMTP. That hardware has been down for a year and is just up and working, all but the email. At the same time most all of my email services have gone through changes.
Hotmail now requires me to use Google to verify and not use the password. And now Google thinks my camera is a "bad actor" and put it on a "bad list" list.
ThunderBird now uses Office 365 for verification and the old password will not work.

Bottom line: What service do you suggest using for smpt email out? Something old school, simple and does not require a third party to verify.

 

I use a VPS from Linode and run my own smtpd. You can get a sufficient VzpS for five bucks a month now. It can do other useful things, too.