حل مشكلة السيرفر لا يرسل ايميلات Fix The 554 Invalid PTR Resource Record Error
554-554-bad dns ptr resource record - (hostname) ESMTP Service not available
554-No SMTP service - 554 invalid DNS PTR resource record
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What is PTR Record?
A PTR Record is the direct opposite of DNS or Domain Name Server. PTR stands for Pointer Record and is an integral part of email server systems. In case of DNS, domains are pointed to their respective IP addresses. But in case of PTR, reverse is true, i.e. IP addresses are associated with their respective domains. These records are used to check if the server is associated with the IP address which initiated the connection. This is an important security protocol both intermediate mail servers and dedicated mail servers follow.
When a mail is send from the sender, it goes through his/her MX, then the recipient’s MX, before finally getting delivered to recipient. If at any of the levels, there’s an error with the PTR, then you’ll get the 554 Invalid PTR Record Error with messages like:
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554-example.com (hostname) ESMTP Service not available
554-No SMTP service
554 invalid DNS PTR resource record, IP=303.0.123.1
المشكلة :
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Many server administrators receive this even after making necessary changes to their IP address and DNS records.
But this error has to do with Reverse DNS, which is also known as PTR.
https://www.rise.company/forum/image.../2022/02/1.jpg
In a normal mail delivery, mail goes from the sender, to the sending MX, and to the recipient’s MX, and finally to the recipient. But, sometimes not all emails reach the destination server. The recipient server performs a series of checks such as PTR or reverse DNS checks, SPF checks, etc. to prevent fraud emails. If the recipient server has doubt in the sender’s authenticity, it rejects such emails and users see the bounce message as below. 554-No SMTP
service 554 invalid DNS PTR resource record
t’s obvious that you have a doubt, what’s this PTR record in the message?
Well, PTR records aka Revers DNS map IP address to domain name and helps to validate a user.
That is, if a server “xyz.servername.com” points to IP address “195.xxx.12x.10x“,
the PTR record of the IP should be “xyz.servername.com“.
So, here the recipient server checks the sender’s PTR record, and either it can’t find the hostname of the IP address,
or the hostname it found doesn’t resolve to the same IP.
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سبب المشكلة :
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The sender has migrated to a new Datacenter and RDNS hasn’t been configured yet.
The server sending the emails has a new IP, but with no PTR records.
The servers were not able to verify the PTR records because there were none in the first place. It’s common for web hosts to not set PTR records for the assigned IP after server migration. With the PTR missing, mail servers treat your IP as spam and hence block the transmission. To fix this problem, you simply have to add a PTR record.
, most major email providers like Hotmail, use this as an important indicator of the source of spam. So, if PTR entry is missing, mail servers deny transport considering this as a major signal of spam.اقتباس:
A common trend we’ve seen with most host providers is they assign a generic PTR for every IP address which is like: “xxx-xxx-xxx-xxx-host.provider.tld”
But when it gets generic for every IP address, then other mail servers treat this as spam since it gets into thinking that this is a dynamic IP address.
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حل المشكلة :
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To solve this problem, you have to change the PTR from a generic to an FQDN (Fully Qualified Domain Name).
An example of this is abc.yourservername.com.
If it’s a Virtual Private Server hosting multiple domains on the same IP address,
you can select the unique hostname of the server and use it as PTR record.
Conclusion
In short, “554 invalid DNS PTR resource record” ocurs due to missing or invalid PTR records. In both cases,
users can’t do much other than contact web hosts or ISPs.
https://youtu.be/dMEzlYYjwxs
التحقق من قيمة ptr من داخل terminal
اذا كان اي بي السيرفر هو 11.22.33.44
فادخله معكوس من اليمين الى الشمال
ثم هتجد ان النتيجة هو اسم السيرفركود:dig PTR 44.33.22.11.in-addr.arpa
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التحقق من قيمة ptr من داخل CMD فى الويندوز
ثم هتجد ان النتيجة هو اسم السيرفركود:nslookup 11.22.33.44
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التحقق من خلال موقع فحص DNS
http://leafdns.com
المرجع:
https://hoststud.com/resources/how-t...ord-error.670/
https://bobcares.com/blog/554-invali...source-record/
https://www.godaddy.com/help/what-is-reverse-dns-2585
https://community.spiceworks.com/top...ecific-address
https://docs.cpanel.net/knowledge-ba...ng-ip-address/
https://support.cpanel.net/hc/en-us/...tom-mail-HELOs
