CinemaVision mail server

[maddin 1]

hi,
I noticed already some time ago, that the mail server this site is using, is not set up correct.
therefor the registration is not working probably. reverse dns seems to be set incorrect. 

Jul 21 20:02:37 mail postfix/smtpd[52592]: warning: hostname dns.xxx.com does not resolve to address xxx: Name or service not known,
Jul 21 20:02:37 mail postfix/postscreen[52453]: PASS OLD [xxx]:4318,
Jul 21 20:02:37 mail postfix/dnsblog[52455]: addr xxx listed by domain list.dnswl.org as xxx,
Jul 21 20:02:37 mail postfix/postscreen[52453]: CONNECT from [xxx]:4318 to [xxx]:25,
Jul 21 20:02:37 mail postfix/smtpd[52592]: connect from unknown[xxx],
Jul 21 20:02:38 mail postfix/smtpd[52592]: Anonymous TLS connection established from unknown[xxx]: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits),
Jul 21 20:02:39 mail postfix/smtpd[52592]: NOQUEUE: reject: RCPT from unknown[xxx]: 450 4.1.8 <cinemavi@xxx.net>: Sender address rejected: Domain not found; from=<cinemavi@xxx.net> to=<info@xxx.com> proto=ESMTP helo=<dns.xxx.com>,
Jul 21 20:02:39 mail postfix/smtpd[52592]: disconnect from unknown[xxx] ehlo=2 starttls=1 mail=1 rcpt=0/1 data=0/1 quit=1 commands=5/7

I had to open up some safety features on my mail server to receive the registration mail.
Anyone who is using "normal" accounts, like gmail, gmx, icloud, etc. will not get these mails. Because it is blocked by anti spam software.

maybe someone wants to take a look at that.
or if help is needed let me know.

cheers