Summary
The 'Domain of sender address does not exist' error arises when the receiving server cannot validate the sender's domain. Root causes include DNS resolution failures due to incorrect or missing DNS records (MX, A), typographical errors in the sender's email address, incomplete DNS propagation for new domains, internal DNS restrictions, issues with the receiving server's infrastructure (MX cluster), use of invalid or non-existent domains, stringent spam filtering requiring valid domain registration, incorrect SPF records, missing PTR records, and lack of email authentication (SPF, DKIM, DMARC).
Key findings
- DNS Resolution Failure: Inability of the receiving server to resolve the sender's domain is the most common cause, due to DNS configuration problems.
- Typographical Errors: Simple typos in the sender's email address, particularly in the domain part, can prevent resolution.
- DNS Propagation Issues: Newly registered domains require time to propagate, causing temporary resolution failures.
- Internal DNS Restrictions: Internal DNS configurations might block external resolution, especially for self-sent emails.
- Infrastructure Issues: Problems within the receiving server's MX cluster can prevent proper domain resolution.
- Invalid Domain: Using a non-existent or improperly configured domain in the 'From' address leads to rejection.
- Stringent Spam Filtering: Receiving servers increasingly verify sender domains to combat spam.
- Authentication Failures: Incorrect or missing SPF records, missing PTR records, and lack of SPF/DKIM/DMARC can lead to rejection.
Key considerations
- Verify DNS Records: Check the sender's domain's MX and A records to ensure they are correctly configured.
- Double-Check Email Addresses: Thoroughly check the sender's email address for any typos.
- Wait for Propagation: Allow sufficient time for DNS propagation if the domain is newly registered.
- Examine Internal DNS: Review internal DNS settings to ensure they properly delegate to external DNS servers.
- Investigate MX Cluster: Contact the administrators of the receiving MX cluster to investigate potential issues.
- Validate Domain Registration: Ensure the domain is properly registered and not on any blocklists.
- Implement SPF: Configure the SPF record correctly to authorize all sending sources.
- Implement PTR Records: Configure a PTR record for the sending IP address.
- Implement Email Authentication: Set up SPF, DKIM, and DMARC to authenticate emails and improve deliverability.
What email marketers say
9 marketer opinions
Emails are rejected with the 'Domain of sender address does not exist' error primarily because the receiving server cannot validate the sender's domain. Common causes include DNS configuration problems (missing or incorrect MX/A records), typos in the sender's email address, incomplete DNS propagation for newly registered domains, invalid or improperly configured 'From' addresses, incorrect SPF records, missing PTR records, and a lack of proper email authentication (SPF, DKIM, DMARC).
Key opinions
- DNS Issues: The most common reason is the recipient server being unable to resolve the sender's domain in DNS. This includes missing or incorrect MX and A records.
- Typographical Errors: A frequent issue is simply a typo in the sender's email address, particularly within the domain portion.
- DNS Propagation: Newly registered domains may not have propagated across all DNS servers, causing temporary resolution failures.
- Invalid 'From' Address: Using an invalid or improperly configured domain in the 'From' address leads to rejection.
- Authentication Failures: Issues with SPF, DKIM, or DMARC can result in the email being flagged as unauthorized and rejected.
- Reverse DNS (PTR) Issues: The absence of a PTR record for the sending IP address can hinder server identity verification, causing rejection.
Key considerations
- Verify DNS Records: Check the sender's domain's MX and A records using tools like MXToolbox to ensure they are correctly configured.
- Double-Check Email Addresses: Carefully inspect the sender's email address for any typos, especially in the domain part.
- Wait for Propagation: If the domain is newly registered, allow up to 48 hours for complete DNS propagation.
- Configure SPF Correctly: Ensure the SPF record is properly configured to authorize all sending sources.
- Implement PTR Record: Configure a PTR record for the sending IP address to enable reverse DNS lookups.
- Implement Email Authentication: Set up SPF, DKIM, and DMARC to authenticate emails and improve deliverability.
Marketer view
Email marketer from SMTP2GO suggests the absence of a PTR record for the sending IP address can result in an email being rejected. PTR records map IPs to domain names and are used to verify the server's identity, meaning that it is a best practice to set it up.
22 Nov 2023 - SMTP2GO
Marketer view
Email marketer from Stack Overflow responds that a "Domain of sender address does not exist" error indicates a DNS configuration problem. The sender's domain either doesn't have valid DNS records or the receiving server can't resolve them, suggesting a check of MX and A records.
8 Nov 2021 - Stack Overflow
What the experts say
5 expert opinions
Emails are being rejected with the 'Domain of sender address does not exist' error due to a variety of reasons related to DNS resolution and domain validity. These include the envelope sender domain failing to resolve in DNS, stringent spam filtering requiring legitimate and properly registered domains, internal DNS configurations blocking external resolution, issues with the MX cluster itself, and problems with DNS propagation for newly registered domains.
Key opinions
- DNS Resolution Failure: The primary cause is the inability of the receiving server to resolve the sender's domain. This can be due to incorrect DNS settings or temporary propagation issues.
- Internal DNS Restrictions: Internal DNS configurations may prevent proper resolution of external domains, especially for self-sent emails, requiring internal DNS adjustments.
- MX Cluster Issues: The problem might not be with the sender's configuration, but with the receiving server's MX cluster having internal failures.
- Stringent Spam Filtering: Modern spam filters are increasingly strict, requiring properly registered and verified domains to prevent rejections.
- Propagation Delays: Newly registered domains require time to propagate across all DNS servers, leading to temporary resolution issues.
Key considerations
- Check Inbound MX Server Logs: Inspect the logs of the receiving MX servers to identify the specific hostname check and error details.
- Examine Internal DNS Configuration: Review internal DNS settings to ensure they properly delegate to external DNS servers for sender domain resolution.
- Contact MX Cluster Administrators: If the issue persists, contact the administrators of the receiving MX cluster to investigate internal problems.
- Ensure Proper Domain Registration: Verify that the sender domain is properly registered, has valid DNS records (MX, A), and is not on any blocklists.
- Allow Sufficient Propagation Time: For newly registered domains, allow sufficient time (up to 48 hours) for complete DNS propagation before sending emails.
Expert view
Expert from Email Geeks shares an experience with Salesforce clients encountering "does not exist" rejections when sending to themselves. This was due to tightly controlled internal DNS not recognizing the zone delegation for the domain/subdomain pointed at Salesforce Marketing Cloud. The solution involved duplicating DNS entries internally or allowing the server to follow the delegation.
10 Mar 2024 - Email Geeks
Expert view
Expert from Email Geeks explains that the rejection message `smtp;553 5.1.8 Domain of sender address does not exist` often indicates the envelope from does not resolve in DNS. They suggest checking the logs on the inbound MX servers for more details about hostname checks and errors. Steve also suggests that the company might have special-cased DNS for their own domains, causing DNS lookup issues internally.
18 Dec 2024 - Email Geeks
What the documentation says
3 technical articles
The 'Domain of sender address does not exist' error (often indicated by a 550 5.1.8 SMTP code) arises when the recipient server cannot locate the sender's domain in the Domain Name System (DNS). This can be caused by several factors, including typographical errors in the email address, sender-side DNS misconfigurations, the domain genuinely not existing, issues related to DNS propagation for newly registered domains, or sender verification failures due to resolver configuration errors.
Key findings
- DNS Resolution Failure: The core issue is the recipient server's inability to resolve the sender's domain via DNS.
- Typographical Errors: Simple typos within the sender's email address (particularly the domain) can lead to resolution failures.
- Sender-Side DNS Issues: Incorrect DNS configurations on the sender's end can prevent successful domain resolution by receiving servers.
- Non-Existent Domain: The domain specified in the sender's email address may not actually exist.
- DNS Propagation Delay: Newly registered domains may not have fully propagated across the DNS system, leading to temporary resolution failures.
- Sender Verification Problems: Failures in sender verification processes (verp) can trigger this error when the receiving server cannot validate the sender's address.
Key considerations
- Verify Email Address: Double-check the sender's email address for any potential typographical errors.
- Inspect DNS Records: Examine the sender's domain's DNS records (MX, A, etc.) to ensure they are properly configured.
- Allow Propagation Time: If the domain is newly registered, allow sufficient time for DNS propagation to complete.
- Check Domain Registration: Ensure that the domain is actively registered and has not expired.
- Review Sender Verification Settings: Investigate sender verification settings and configurations for any potential misconfigurations.
Technical article
Documentation from Microsoft Learn explains that the '550 5.1.8' error (Domain of sender address does not exist) indicates that the sender's email address domain is not found in DNS. This can occur due to typos in the email address, DNS configuration issues on the sender's side, or the domain genuinely not existing.
21 May 2022 - Microsoft Learn
Technical article
Documentation from cPanel Documentation explains that the "Domain of sender address does not exist" error (550 or similar) means the recipient server cannot resolve the sender's domain. This could be due to DNS issues, a newly registered domain that hasn't propagated, or the sender using a non-existent domain. Check DNS records and domain registration.
23 Oct 2022 - cPanel Documentation
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