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How to troubleshoot intermittent email delivery failures caused by SPF and DNS issues?

Summary

Intermittent email delivery failures, especially those linked to SPF and DNS issues, often point to underlying complexities that aren't always straightforward. While your own SPF records and DNS configurations might appear healthy, the problem can sometimes lie with the recipient's mail server or DNS resolver infrastructure. These issues can manifest as temporary rejections (tempfails) which eventually succeed on retry, making them difficult to diagnose without in-depth analysis of DNS query behaviors and server responses.

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What email marketers say

Email marketers often face the frustrating challenge of intermittent delivery issues, particularly when their own setup appears to be compliant. Their experiences highlight the nuances of SPF and DNS interactions, revealing that perceived 'healthy' configurations can still encounter problems due to external factors or specific recipient server quirks. The common thread is the need for persistent monitoring and re-evaluation when initial checks show no apparent errors.

Marketer view

An email marketer from Email Geeks notes that despite having no issues with delivery to other domains, a specific domain consistently causes problems, leading them to suspect an issue with their SPF record.

03 May 2019 - Email Geeks

Marketer view

An email marketer from Spiceworks Community reports intermittent rejections of their Office 365 mail due to perceived missing SPF records, indicating a potential configuration or recipient issue.

15 Apr 2024 - Spiceworks Community

What the experts say

Experts in email deliverability underscore that intermittent SPF and DNS related failures are often symptoms of complex interactions between sender configurations and recipient infrastructure. While a sender's DNS may appear robust, slow or inconsistent responses from certain nameservers, or issues with a recipient's local DNS resolver, can lead to sporadic rejections. These are often outside the sender's direct control but contribute significantly to delivery problems.

Expert view

An expert from Email Geeks identified DNS timeouts for a specific domain, noting that it occurs inconsistently but has happened several times, with the timing out nameserver being a root server.

03 May 2019 - Email Geeks

Expert view

An expert from SpamResource.com advises that SPF PermError (too many DNS lookups) and TempError (temporary DNS issues) are common causes of email authentication failures and should be meticulously investigated.

18 Mar 2024 - SpamResource.com

What the documentation says

Technical documentation and research frequently highlight that intermittent email delivery failures stemming from SPF and DNS issues are often rooted in the dynamic nature of DNS resolution and the varied implementations across mail systems. These sources emphasize the importance of strict adherence to RFCs for SPF record syntax and DNS behavior, while also acknowledging the practical challenges posed by diverse network conditions and recipient server configurations that can lead to transient lookup problems.

Technical article

Documentation from AutoSPF indicates that common errors when creating SPF records, such as improper syntax or incorrect order of mechanisms, can lead to authentication failures.

01 Nov 2024 - AutoSPF

Technical article

DuoCircle documentation on DMARC TempError states that these refer to temporary authentication issues related to email standards like DKIM and SPF, causing DMARC validation failures.

15 Mar 2025 - DuoCircle

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