> It's pretty common knowledge that if you need to send mission critical email, you should use a service specifically designed for that. Sending email programmatically directly from a web server has ALWAYS been a gray area.

I partially agree with this - dedicated email services have a higher deliverability rate than a random web server, especially a cloud-based server that might be using an external IP that was previously used to send spam. However, I can understand the parent poster being annoyed that their emails were being delivered one day, and not the next, without any changes on their end.

> At the VERY least you could have easily set up a gmail account and sent them from smtp. Choose the right tool for the job.

This is absolutely the wrong tool for the job. You should not be using a Gmail account to send out automated emails that you care about.