I had my personal domain hosted with Google years ago. One of the reasons I moved away is that emails that I was sending to other Google Apps domains were bounc

I had my personal domain hosted with Google years ago. One of the reasons I moved away is that emails that I was sending to other Google Apps domains were bouncing as spam when the destination address was an alias. The bounce came from Google Groups, which is what Google used for handling aliases within Apps domains. e.g. https://pastebin.com/u48DAaLP https://pastebin.com/u48DAaLP That particular example was sent via SMTP, but I had the same problem when sending via the Gmail web interface, and it occurred sending to at least three different Google Apps domains. After I moved my domain off Google Apps (I switched to Fastmail for a variety of reasons, but that issue was the kicker), I was able to send to those same addresses without issue. In fairness to Google, I was on the Google Apps free tier at the time, so there was nowhere to go for support.