First of all, thanks very much for the explanation 
.
So, after reading it, in my case, where I’m only hosting a private server for friends a family I assume I’m OK with just two entries:
- The A record for my domain.
- The opendkim record so that delta chat clients use DKIM (which IINM is needed for push notifications at mobile phones).
I’m going to try with those two and the configuration I got from the script and see what happens 
Will come back with more news…