@girish good point. here's what is returned on the cloudron server at my.domain.com:
$ host box.domain.com
box.domain.com has address [correct IP address for MIAB machine]
box.domain.com mail is handled by 10 box.domain.com
[correct ip address for MIAB machine] is of course definitely not 127.0.1.1
re: custom DNS
the Mail-in-a-Box server at box.domain.com controls the DNS for domain.com and otherdomain.com (standard for MIAB to control DNS) and there are custom DNS entries....
However, the only custom DNS records are the wildcard A records (1 for each domain) pointing to the same cloudron server.
Thus the "host" command on the cloudron machine returns the expected IP addresses for the Cloudron and MIAB servers based on the domain/subdomain pinged.
Host is Vultr in case that provides any clues. The servers are in the same geographic location listed by Vultr.
My current hypotheses (which likely aren't worth much):
- Error message is not returning the expected information (has happened before will happen again)
- there's something going on with the container isolation strategy you guys are using that isn't playing nicely with the network.... but you'd know way more about that than me.
I'm going to run with the firewall idea to see if that leads to a fix so that can be counted out and will report back.