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Why are emails bouncing with 'domain does not exist' or 'invalid sender domain' errors?

Summary

Emails bouncing with 'domain does not exist' or 'invalid sender domain' errors can be a frustrating issue, often appearing suddenly even when no changes have been made to your DNS records. These hard bounces indicate that the recipient's mail server cannot resolve or validate the sender's domain, leading to a permanent delivery failure. While it might seem like a recipient problem, the root cause usually lies with the sender's domain configuration, particularly related to the return-path (also known as the envelope-from) domain.

What email marketers say

Email marketers often encounter these 'domain does not exist' or 'invalid sender domain' bounces and typically approach them with systematic troubleshooting. Their experiences highlight the common pitfalls and immediate checks required when such issues arise, especially when no direct changes were made to DNS. The focus is usually on verifying the integrity of sender-side configurations and understanding the specific bounce responses from recipient servers.

Marketer view

An email marketer from Email Geeks notes that they recently observed similar bounce increases with SBCGlobal and Verizon, suggesting it might be a broader issue affecting certain ISPs.

03 Oct 2019 - Email Geeks

Marketer view

An email marketer from EduGeek.net suggests that if the recipient's domain exists and works for others, the issue might be a mistyped or incorrect email address on the external sender's part, possibly cached incorrectly.

15 Mar 2025 - EduGeek.net

What the experts say

Email deliverability experts emphasize the critical role of proper DNS configuration, particularly for the return-path domain, in preventing 'domain does not exist' and 'invalid sender domain' bounces. They look beyond superficial checks, delving into the intricacies of DNS propagation, potential temporary glitches, and the behavior of remote mail servers and forwarders. Their advice often steers towards meticulous validation of all associated domain records.

Expert view

An expert from Email Geeks suggests checking the MX records for the return-path domain, indicating that missing or incorrect MX records are a frequent cause of these errors.

03 Oct 2019 - Email Geeks

Expert view

An expert from Spam Resource discusses the importance of proper DNS settings, including MX records, for email deliverability, noting that incorrect configurations can lead to messages being rejected.

20 May 2024 - Spam Resource

What the documentation says

Official email documentation and technical standards define the proper behavior of mail servers and the meaning behind specific bounce codes. These resources provide the foundational understanding of why 'domain does not exist' or 'invalid sender domain' errors occur, typically pointing to issues where the sending domain fails fundamental DNS queries or authentication checks as mandated by internet protocols and receiving server policies.

Technical article

GitHub documentation on Postal (an email server) suggests that errors like 'Domain of sender address does not exist' occur when the recipient's server checks the existence of the envelope-from domain. It implies resolution might require adding an MX record and/or an A record.

20 May 2017 - GitHub

Technical article

SendLayer documentation defines hard bounces as occurring when emails are permanently undeliverable due to reasons such as an invalid or non-existent email address, which includes the domain part of the address.

10 Nov 2023 - SendLayer

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