I don't know of any issues. One of the companies I had (5-6 years ago) used a .io address and had email with no issues. In fact we sent a lot of marketing ema

I don't know of any issues. One of the companies I had (5-6 years ago) used a .io address and had email with no issues. In fact we sent a lot of marketing email as a .io domain and never had any troubles. Just like anything we had to get the email configuration solid, but after that it was smooth. I'd be interested in hearing any reasons you find stating the opposite. FWIW too, we hosted within AWS and used Route53 just like I do for most projects.