Resolved Forward-confirmed reverse DNS failed tnmpmscs

[Mark R]

Hi, Can anybody help please

Email rejection error message 'Forward-confirmed reverse DNS failed tnmpmscs'

Plesk is installed on an Ionos VPS
Cloudflare is hosting DNS

Plesk Full Hostname is server.myplesk.com
Ionos Reverse DNS is server.myplesk.com

I have two websites running on Plesk both of which have emails rejected with error 'Forward-confirmed reverse DNS failed tnmpmscs'

Mail-tester.com results.
1) -1.274 RDS_NONE, Delivered to internal network by a host with no rDNS
2) Your server *.*.*.196 ( Plesk IP address) is successfully associated with server.myplesk.com, This may indicate you do not have a rDNS configured for your hostname or the rDNS does not match your sending IP

PTR has been set to the main Plesk IP address of the server, is this correct?
Is this a PTR issue?

Any help would be appreciated

 

[Kaspar]

Your issue seems to match the case described in: https://support.plesk.com/hc/en-us/...dress-to-which-the-chosen-hostname-resolves-2

Do you have Cloudflare poxy enabled for server.myplesk.com? Or are there any other DNS records (either for IPv4 or IPv6) that point to different IP addresses?

 

[Mark R]

Hi,
Typo should read

1) -1.274 RDS_NONE, Delivered to internal network by a host with no rDNS. This may indicate you do not have a rDNS configured for your hostname or the rDNS does not match your sending IP

2) Your server *.*.*.196 ( Plesk IP address) is successfully associated with server.myplesk.com

 

[Mark R]

Hi,

server.myplesk.com is not proxied

the entry looks like this
server.myplesk.com.myfirstwebsite.co.uk

All DNS in cloudflare reference my main Plesk IP

 

[Kaspar]

PTR has been set to the main Plesk IP address of the server, is this correct?

No. You don't need an PTR record.

At your IONOS account make sure you've added the hostname of you plesk server (server.myplesk.com) as the Reverse DNS of you Public IP. See: Overview: Public IP (VPS, migrated Cloud Servers, and VPS+) - IONOS Help

 

[Mark R]

Hi,
already done.

Plesk Full Hostname is server.myplesk.com
Ionos Reverse DNS is server.myplesk.com

 

[Kaspar]

If you use a DNS lookup tool to check the Reverse DNS of your IP, does show your server hostname. For example you can do a Reverse DNS lookup with: Reverse IP Lookup - MxToolbox

And similarly, if you use a DNS lookup tool to check lookup the hostname of the server, does it only return one IP (and is it the same IP as you on which you've set the Reverse DNS)? You can do a DNS lookup with: DNS Lookup Tool - DNS Tools - MxToolbox

 

[Mark R]

Hi,

My IP resolves to server.myplesk.com

server.myplesk.com resolves to 2 x IP'S both of which are showing as Cloudflare

*****

I apologies now fixed...

You asked me to check to see if server.myplesk.com was proxied in Cloudflare but I only checked this in my websites for which I was sending emails from, not the main domain DNS for the server (mypleskserver.com)

mypleskserver.com WAS proxied (now not proxied has fixed the problem)

websiteone.co.uk not proxied
websitetwo.co.uk not proxied

Even though working now, I'm a little confused do I need to put server.myplesk.com in my websiteone.co.uk/websitetwo.co.uk DNS records?

the entry looks like this
server.myplesk.com.websiteone.co.uk


Thanks for your help!

 

[Kaspar]

Glad to hear you've got it sorted.

Even though working now, I'm a little confused do I need to put server.myplesk.com in my websiteone.co.uk/websitetwo.co.uk DNS records?

the entry looks like this
server.myplesk.com.websiteone.co.uk

No, no need to reference the host name of the server in the DNS zone of your websites. You can safely remove those records.