550 reverse dns lookup on sending mailserver failed

SMTP Error Messages of the 1&1 IONOS Mail Servers

This way receiving end can make sure that your email server is authorized to send an email for cyberhosting. We will discuss those records one by one. It basically lists IP Addresses of the server s authorized to send emails on behalf of a said domain. In this example, you are allowing IP Address Thus this record is very important if you want to make sure that emails are delivered properly.

It is a mechanism that allows the receiving end to check that an email was actually sent and authorized by the owner of the domain, thus another level of protection on top of SPF. If receiving end can make sure that email is signed with a valid DKIM signature, it guarantees that parts of emails have not tampered and the original message is received. So it is highly recommended to use DKIM record along with SPF to improve email deliverability and at the same time prevent any spam that can originate from your domain. RDNS record is very important in email delivery.

This record is set by the owner of the IP, in this case, your cloud provider or if you are our customer we can set this record for you.

Email fails with: Warning - Reverse DNS lookup failed for host

We will also help you to set all the remaining records too and make sure your server is ready to deliver emails properly. In any other case, it would be considered insufficient. In short make sure you have following records set, so the receiving end can make sure that you are the actual owner of the domain email is being sent from, otherwise, the receiving end may think that you are using someone else domain to send spam email.

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Reverse lookup is based on the IP from which your mail server is sending from. If so, I would recommend you use a smart host for sending out mail. . dequadmochito.tk and not dequadmochito.tk which is what rDNS is set to and that's causing the failure. Sender IP reverse lookup rejected. Email fails with: Warning - Reverse DNS lookup failed for host There was a SMTP communication problem with the recipient's email server. . If you check my MX record, you will notice that the instruction is to send it to.

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Outgoing email messages are rejected with a message “Relaying denied. IP name possibly forged”

A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. Sending server IP blacklisted. Sender server issues. Tuesday, January 6, PM. All replies. Also ensure that the PTR records in your external dns are configured correctly.

Regards, Johan blog: www. Hi, The most likely cause could be that your server may be listed as a spamming server. I say this based on some of the error messages we saw for the undelivered messages in the queues. Tuesday, January 6, AM. And this worked thanks at this time. But, why is exchange not able to resolve this mx of the domain? I tried nslookup on the exchange and on his dc and get "DNS request timed out. But the other errors didn't disappear The result is negative, the IP is not listed. Could it be a problem, when the MX record points to a system linux in the dmz and the hub transport does send directly to the internet?

Both has an own host name which is registered with a PTR record for reverse dns Hi, Yes this could be a problem indeed. Did you try to relay the mail via the server in the DMZ? Hello I did some test with sending emails directly to the remote server with telnet. It's the outbound the one that is connecting to other machines - that needs the reverse lookup. For most small businesses, these are the same.

Direct Delivery

The main causes are usually outdated address lists for newsletters and other mass mailings or compromised mailboxes that are misused to send spam. See RFC Super User works best with JavaScript enabled. So, the company that owns this IP sets this record. Is my only hope to use an address with a domain on the VPS, i. Try to pick a name for this subdomain that represents the type of email you will send using this new domain whitelabel.

It's perhaps more accurate to say as a commenter did below the PTR record should match the SMTP response on port 25 when the receiving server sends back a verification check. However, it is usually only necessary that the record exist and not contain "in-addr.

Your Answer

See the comments below. How do you get a PTR record? You might think that this is done by your domain registrar - after all, they point your domain to an IP address. Or you might think whoever handles your DNS would do this.

They are the ones who need to create the PTR record. In some cases, that may be the same folks who handle your DNS, but the point is that it is not necessarily so: you may have no control over this whatsoever. See RFC If you don't have a PTR record, and can't get one for example because you have a dynamic address , you will want to send outgoing email through a server that does. However, assuming that you aren't blocked for outgoing SMTP, you can use any server that "likes" you - that is, any server that will allow your IP address to relay mail through it.

That's probably going to be another server under your control, or someone who knows you - there are few servers left that will let just anyone use them as a mail relay.

How to set up reverse DNS

These are records you can add to your own dNS and they help prevent people masquerading as your mail server. Servers that check these records not all do know when it really is your server that sent the mail; it is therefore less likely to be refused. See Google's Additional guidelines for IPv6 , for example. It contains technical articles about Unix, Linux and general computing related subjects, opinion, news, help files, how-to's, tutorials and more.

You learn about life by the accidents you have, over and over again, and your father is always in your head when that stuff happens. Kurt Vonnegut. Basic DNS: PTR records and why you care I've removed advertising from most of this site and will eventually clean up the few pages where it remains.

How to configure your outgoing mail server in WHM (SMTP) - WHM Service Tutorials

If you found something useful today, please consider a small donation. It's a very common practice to use separate inbound and outbound servers in an email environment. Whether this was a common practice or not in is questionable; however, having been in the spam filtering industry for the past 3 years, I have NEVER come across a case where the MX record was in fact being compared to the PTR record.

This is a very common misconception hence, the reason for my comment today. Reverse DNS containing in-addr. Reverse DNS consisting of IP addresses are also not acceptable, as they do not correctly establish the relationship between domain and IP address. Source: link Hope this helps someone in the future.

Most of the people that have this problem are small, and run ONE server, so for them it's simpler to explain it this way.