We've recently started using alldomains.hosting for what we call "programmatic emails". For that purpose alldomains.hosting is dirt cheap (~1€/year/email address), which makes one quite motivated to suffer through the confusing website to figure out how to buy stuff from them. Once you've managed to buy your domain and/or mail services they just "tend to work". Alldomains.hosting IPv6 support, or lack of it, may be a problem for you, though.
For example, in AWS EC2 you nowadays really want to avoid assigning public IPv4 addresses to EC2 instances as they cost quite a lot. So, you set up an IPv6-only egress-only internet gateway in your VPC and, for the most part, everything "just works". Then you try to add mail delivery via alldomains.hosting and IPv6 and "boom", it does not work. According to their support (as of 25.9.2024) their mail servers lack IPv6 support.
So, unfortunately alldomains.hosting IPv6 support (at least for email delivery) is completely missing. So, if you're dreaming of SMTP over IPv6 just use some other service provider. If you're already committed you can work around this limitation, e.g. by using a relay host, but that's extra work. If you're an existing alldomains.hosting customer I encourage you to contact their support and request IPv6 for their mail servers. Otherwise they keep on thinking that nobody uses IPv6.
