Just set it up about a week ago on a separate DigitalOcean droplet (one-click installation, now I’m on Version: 2.6.0.beta1 (310952fd6a). I use a subdomain and have the DNS records also on DigitalOcean. I have an A-Record, pointing to the IP, MX-Record pointing to the sub-domain name for reply by email as per these instruction). Only thing there is that I don’t have a DMARC Record published.
That’s all I can think of that I did in relation to DNS stuff. However, so far everything worked as expected. The site is set up, I can reach it via the sub-domain name, log-in, create topics (even via email), etc.
I’m just startled the first message made it through, but subsequent ones didn’t 