<user@domain.ru>: Host or domain name not found. Name service error for name=user@domain.ru type=AAAA: Host not found

[calport]

If the problem of sending out mail is server wide then you should check if your service provider has blocked port 25. See:

Free smarthost / mail relay to work around port 25 block by VPS host

If your VPS host (AWS, OVH, Vultr, Bluehost, Digital Ocean et al) is blocking port 25 and this is causing problems with your Virtualmin installation and testing, I will be happy to offer you free smarthost / mail relay service for testing or low volume email. To get started, you will need to send me the IP address of your Virtualmin box (VPS) and the list of domain names which will be authorized to send email. I will then give you the IP address of my Virtualmin box and the SPF and DKIM records…