RoundMail gives an error, how to fix it?

Question

System administration

I bought vps in vscale, chose the installation with the vesta socket. (ubuntu 16.04). The site works fine, but the mail is not sent :c
I contacted support, they told me to register a PTR record of this type mail.domain.ru, but this did not help.

When trying to send

help please :c

Answer 1

Well, firstly, the PTR record is rdns, it cannot be of this type mail.domain.ru
Secondly, how could you register it and where? if the current provider who gave you the IP address can prescribe it.
Thirdly, not only does the roundcube have its own logs, but it also has regular mail logs, see their /var/log

Answer 2

https://www.mail-tester.com/

Answer 3

You write an error in English in white:
https://www.google.ru/search?q=550+5.7.1+invalid+h...
https://major.io/2006/12/26/fixing- invalid-helos/