I use my nameservers and when sending emails the domains that I have don’t use the IP that’s in the default SPF record. I use additional IPs for this purpose.
I was able to change the default SPF records at /usr/local/hestia/data/templates/dns and the changes show under “DNS - DNS records” but under “Mail - DNS records” it still shows the default SPF record that is there after installation.
The emails now validate with the correct SPF record but need help on where to edit the SPF record so that it shows under Mail - DNS records too.
For me, yes, every domain has its own space. I don’t hace customers but I suppose them would prefer to access their webmail using their own domain, also, doing that you can configure roundcube to use only user as user name instead of user@domain.
Try it, connect to one of your webmail urls and use user@anotherdomain and you should be able to login with that user that belongs to another domain ( I really hate to write the domain part when I want to login to webmail )