Hi.(My apologies for my bad English. It is not my native language) I need your advice and your guidance, how to approach the situation and how to proceed further. I have two separate servers, with Debian 11 and ISPConfig 3.1 Recently, a few days ago, a user sent an email to a new customer, and I instantly received a rejection email. That email was a reply, after the customer placed a commercial order on our website. "office@customerdomain. dot ro>: host mail.customer dot ro[77.81.xx.xx] said: 554 5.7.1 Service unavailable; Client host [220.127.116.11] blocked using spam.spamrats dot com; SPAMRATS IP Addresses See: www.spamrats dot com/bl?18.104.22.168 (in reply to RCPT TO command)" I checked the logs, checked the blacklists and found that everything is fine except for spamrats, which did not necessarily block our e-mail servers, but the entire class of IPs of our ISP. I had a discussion with our ISP and he told me, after the checks, that everything is clean. No attack, no abuse, no infection on that class of ips. I have checked my IP in SpamRATS and the result is the following: Standards Compliance: Does IP Address resolve to a reverse hostname... Passed! Does IP Address comply with reverse hostname naming convention...Passed! List Status: RATS-Dyna - On the list. Worst Offender Alert RATS-NoPtr - Not on the list RATS-Spam - Not on the list No delisting method works on the SpamRats website.I wrote to them on the contact page and they did not reply. I sent them an email from gmail to abuse@spamrats dot com and they didn't reply. Some reviews on the Internet about SpamRats look like this: "SpamRats is a very unreliable blacklist. They basically ignore everyone including ISPs, so there are always a good number of innocent sites listed by their system. Ignore or remove Spamrats and use the more reliable lists like Spamhaus, SpamCop, Truncate, UCEprotect." "SpamRats is a cheating "company" that is adding whole IP ranges and after than they try to sell you commercial services provided by their official companies ... if you write them an email with demand to stop illegal discreditation of the good name of your company or you will sue them they will remove it within an hour ... personal experience" OK until this step. I don't use SpamRats in SpamAssassin. In PostFix main.cf i have this line: smtpd_client_restrictions = check_client_access proxy:mysql:/etc/postfix/mysql-virtual_client.cf, permit_inet_interfaces, permit_mynetworks, permit_sasl_authenticated, check_client_access regexp:/etc/postfix/rbl_override, reject_rbl_client sbl.spamhaus org, reject_rbl_client xbl.spamhaus org, reject_rbl_client rbl.abuse ro, reject_rbl_client zen.spamhaus org, reject_rbl_client bl.spamcop net, reject_rbl_client psbl.surriel com, reject_rbl_client dnsbl-1.uceprotect net, reject_rbl_client cbl.abuseat org, reject_rbl_client dnsbl.justspam org, reject_rbl_client bl.mailspike net, reject_rbl_client spam.dnsbl.anonmails de, reject_rbl_client ix.dnsbl.manitu net, reject_rbl_client truncate.gbudb net, reject_rbl_client bl.blocklist. de, reject_rhsbl_client hostkarma.junkemailfilter com=127.0.0.2, reject_rhsbl_sender hostkarma.junkemailfilter com=127.0.0.2, reject_unauth_pipelining, permit Our mail servers meets all the technical conditions of operation, in terms of national and international regulations. Our email server, have DNS PTR registration, SpamAssassin filters, Mail Antivirus, SPF valid DNS registration, DKIM and dmarc record. We use our mail servers only for communication inside the organization and for communication with our clients on a 1:1 basis. We do not have mass-email campaigns, and we don't do either advertise by email. Even if I have the e-mail server and the dns server configured correctly, I can expect that the first mail sent to a new customer will end up in spam. Possibly..., even if it hasn't been the case so far. But in this situation it was like a trap. First attempt - first shot and that's it. We are in the blacklist. Why? What is the clear reason? Evidence of spam? We can ignore SpamRats, but what do we do about communicating with our future clients who use SpamTrap on their email servers? We believe that this will affect the smooth running of the business we own. We had e-mail services at Google for domain, Other domains, we had them at other hosting providers with Cpanel, but we did not have clear control over e-mail whitelist customers, and we were not receiving some e-mails from customers. That's why we chose to host our server ourselves. Since SpamRats services are hosted in Canada, we would like to file a complaint with the appropriate authorities in Canada: ised-isde.canada dot ca/site/competition-bureau-canada/en/restrictive-trade-practices I would still like to hear your opinion. There may be a simpler solution.