The docs say: "By default a set of typical records is created for each hosted domain with MX records pointing to the local system, and aliases such as www. and ftp. for convenience. If you wish you may edit the records to make custom additions or otherwise make changes to those defaults."
I can see the generated DNS records in "my-brilliant-site.com.txt" and indeed edit them. I'm not clear though in what circumstances they might get overwritten by symbiosis-dns-generate, which the docs say runs hourly.
For example, if my mail server is elsewhere, how would I ensure that the script leaves my custom MX records intact and does not try to insert, for example, the ip6 MX address for exim on BigV?