I've added that domain, and the go subdomain, to your account for you. Please note that it may take up to 2 hours for them to fully work. If after a full 2 hours they don't work on your side, please make sure you clear your web browser cache: https://wiki.helionet.org/Clear_Your_Cache
In the meantime, please make sure you configure DNS for them. You can either:
Set NS records pointed to the HelioHost nameservers: `ns1.heliohost.org` and `ns2.heliohost.org`, or
Manually create DNS records:
Add an A record (IPv4) pointing to your server's IPv4 address.
Add an AAAA record (IPv6) pointing to your server's IPv6 address.
To find the correct IPs, please go to: Login > Plesk > Websites & Domains > [domain name] > and check at the bottom of the page.
The "webmail" subdomain is reserved for Plesk's Roundcube. If you planned to use a different service, we recommend using your account's server name ('tommy.heliohost.org') as the host address anyway. You can view our email accounts guidance page for more details, but please let us know if you have any questions.