I have a VPS with Plesk Onix in OVH, two IP, one for each domain. With the second domain I can send and receive emails without problems but the other day I found that the emails are bounced when sent to a specific email that surely has a security type other than most.
Action: failed
Status: 5.0.0
Remote-MTA: dns; correodestino.com
Diagnostic-Code: smtp; 550-"JunkMail rejected - ip206.ip-144-217-101.net
(procode.com.uy) 550-[144.217.101.206]:51978 is in an RBL on
550-csi.cloudmark.com/reset-request/?ip=144.217.101.206 , see Poor
Reputation 550 Sender"
When analyzing the mail in search of possible bans or that has been included in blacklists, I find that it is not like that. When I analyze the mail in mail-tester.com I find it good, except for a wake-up call that the mail is not coming with the header that corresponds to its IP but with the header of the other domain that has its own IP:
Your IP address 144.217.101.206 is associated with the domain ip206.ip-144-217-101.net. However, your mail seems to have been sent from procode.com.uy.
You may want to change your pointer DNS entry (PTR type) and the hostname of your server at the same value.
Here are the values tested for this test:
IP: 144.217.101.206
HELO: procode.com.uy
rDNS: ip206.ip-144-217-101.net
Both domains do not have PTR records and I do not know about them. Create a PTR record for the second domain (the one with the problems) but keep everything the same. Do you have any idea that you may be failing?