The seller of my domain name has a web based GUI for configuring the DNS 'A' records to my VPS server. I have set this up as per the screenshot attached.

However, when I test the mail server on mxtoolbox, it tells me that the "Reverse DNS does not match SMTP Banner". It appears that the SMTP Reverse DNS resolves to the address of another mail server that I have hosted on the same VPS.

I have multiple domains hosted on the same server, and Bind9 is installed.

I presume I need to configure Bind to serve up the correct Reverse DNS?

First of all, are the DNS Records shown below in a valid configuration? And, secondly, how do I go about configuring Bind if it is.

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If your server has IP "a.b.c.d" then the reverse lookup is done for the PTR record at "d.c.b.a.in-addr.arpa". This will resolve to a single FQDN (hostname). Your bind does not control the in-addr.arpa space; that is managed by your ISP. SMTP makes no provision for hosting multiple mail servers on the same IP. How would it separate incoming messages?