Summary
Third-party email signature services, such as Exclaimer, can significantly impact email deliverability through several mechanisms. These services route emails through their servers, which can lead to SPF failures unless the SPF record is updated to include their sending servers. They can also alter email content, potentially invalidating DKIM signatures, and contribute to DMARC failures if SPF and DKIM are not properly configured. Furthermore, large signatures with embedded images increase email size, triggering spam filters. Receiving issues are unlikely related to signature services. Troubleshooting often requires detailed data about delivery failures. Properly managing DKIM signing post-signature insertion, optimizing signature size, and adhering to IT policies are crucial for maintaining deliverability. Forwarding, structural quirks, and non-whitelisted links also play roles.
Key findings
- SPF Failures: Third-party signature services can cause SPF failures due to routing emails through their servers.
- DKIM Invalidations: Altering email content through signature services can invalidate DKIM signatures.
- DMARC Failures: Improper SPF and DKIM configuration can lead to DMARC failures and reduced deliverability.
- Signature Size Issues: Large signatures with embedded images can trigger spam filters.
- Forwarding Impacts SPF: Email forwarding can break SPF, causing authentication problems.
- Whitelabeling Impact: Lack of whitelabeling Exclaimer links could negatively impact your deliverability
Key considerations
- SPF Record Updates: Update SPF records to include the sending servers of the third-party email signature service.
- DKIM Management: Ensure the signature service properly manages DKIM signing after signature insertion.
- Optimize Signature Size: Optimize signature size by using linked images instead of embedded ones.
- Monitor Authentication: Regularly monitor authentication reports to identify and address deliverability issues.
- Gather Delivery Data: Gather detailed data on delivery failures for effective troubleshooting.
- Evaluate IT Policies: Evaluate any IT policies such as blocking base64 encoded content.
What email marketers say
8 marketer opinions
Third-party email signature services can significantly impact email deliverability. Issues arise from rewriting emails, which can cause SPF and DKIM failures, ultimately leading to emails being marked as spam. Large signatures with embedded images can increase email size, triggering spam filters. Proper configuration of SPF and DKIM, optimizing signature size, and monitoring authentication reports are crucial. Alterations of email content by these services can invalidate DKIM signatures, necessitating solutions such as DKIM signing after signature insertion.
Key opinions
- SPF/DKIM Failures: Third-party signature services can cause SPF and DKIM failures due to email rewriting.
- Spam Marking: Emails with improperly configured signatures are more likely to be marked as spam.
- Signature Size: Large signatures with embedded images can increase email size and trigger spam filters.
- DKIM Invalidation: Email signature services can alter email content, invalidating DKIM signatures.
Key considerations
- Proper Configuration: Ensure proper configuration of SPF and DKIM when using third-party signature services.
- Optimize Size: Optimize signature size by using linked images instead of embedded ones.
- Monitor Authentication: Regularly monitor authentication reports to identify and address deliverability issues.
- DKIM Signing: Implement DKIM signing after the signature service has processed the message, or use a service that offers this feature.
- Testing: Test email deliverability with and without signatures to assess impact.
Marketer view
Email marketer from StackOverflow explains the challenges of email signature services altering email content, which can invalidate DKIM signatures. Suggesting using a service that signs the email after signature insertion or implementing DomainKeys Identified Mail (DKIM) signing after the signature service has processed the message.
5 Feb 2022 - StackOverflow
Marketer view
Email marketer from Mailtrap.io shares that third-party email signatures can rewrite emails and cause authentication problems, potentially resulting in emails being marked as spam. Proper configuration of SPF and DKIM is crucial when using these services.
11 Sep 2024 - Mailtrap.io
What the experts say
10 expert opinions
The use of email signature services like Exclaimer can introduce complexities affecting email deliverability. While Microsoft 365 reapplies DKIM after Exclaimer's processing, potential issues include DMARC failures if DMARC policy is set to reject and the service strips DKIM before forwarding. Structural issues and non-whitelisted links within signatures may also contribute to deliverability problems. Troubleshooting requires detailed data on delivery failures, and receiving issues are often unrelated to Exclaimer. IT policies, such as blocking base64 encoded content, might also impact email display. Proper DKIM management by the signature service and avoiding forwarding that breaks SPF are crucial for maintaining deliverability.
Key opinions
- DKIM Reapplication: Microsoft 365 typically reapplies DKIM after Exclaimer processes emails.
- DMARC Policy Impact: Stripping DKIM before forwarding with a 'p=reject' DMARC policy can cause deliverability issues.
- Signature Structure: Janky email structures and non-whitelisted links in signatures may impact deliverability.
- Limited Exclaimer Impact: Receiving issues are likely unrelated to Exclaimer Cloud.
- SPF Breaks: Forwarding can break SPF, causing deliverability problems.
Key considerations
- Data for Troubleshooting: Gather detailed data on delivery failures, including rejection messages and affected domains/IPs.
- IT Policy Review: Check for IT policies that may impact email display, such as blocking base64 encoded content.
- DKIM Management: Ensure the email signature service properly manages DKIM signing after signature insertion to avoid invalidation.
- Avoid Forwarding Issues: Avoid forwarding that breaks SPF.
- Whitelabeling: Whitelabel the signature domain.
Expert view
Expert from Email Geeks states that the ball is in IT’s court and there’s not really anything you can do without more detailed data on the delivery issues.
15 Jul 2023 - Email Geeks
Expert view
Expert from Email Geeks suggests that receiving issues are likely unrelated to Exclaimer Cloud.
26 Jul 2024 - Email Geeks
What the documentation says
5 technical articles
Email signatures, particularly those managed by third-party services like Exclaimer, can introduce complexities that affect email deliverability. A primary concern is SPF failures, as emails may appear to originate from unauthorized servers, necessitating SPF record updates to include the service's sending servers. Additionally, email forwarding and any modifications to message content post-DKIM signing can invalidate DKIM signatures. Proper configuration of SPF and DKIM is crucial to avoid DMARC failures and maintain deliverability, especially when using these services, and misconfigured DNS records related to email signatures can lead to deliverability issues.
Key findings
- SPF Failures: Third-party email signature services can cause SPF failures as emails are routed through different servers.
- DKIM Invalidations: Email forwarding and modifications to the message content after DKIM signing can invalidate the signature.
- DMARC Failures: Incorrect SPF and DKIM configuration when using third-party services can lead to DMARC failures.
- DNS Issues: Misconfigured DNS records related to email signatures can cause deliverability issues.
Key considerations
- SPF Record Updates: Update SPF records to include the sending servers of the third-party email signature service.
- DKIM Configuration: Ensure proper DKIM signing is implemented, considering modifications to the message content.
- Authentication: Carefully configure SPF and DKIM to ensure proper authentication when using third-party services.
- Avoid Forwarding: Avoid forwarding where possible to limit DKIM issues
Technical article
Documentation from DMARC.org highlights that using third-party services, including those that add email signatures, requires careful SPF configuration to ensure proper authentication. Failing to do so can result in DMARC failures and reduced deliverability.
18 Aug 2021 - DMARC.org
Technical article
Documentation from Exclaimer.com explains that when using a third-party email signature service like Exclaimer, emails are routed through their servers, potentially causing SPF failures because the email appears to originate from a different server than the domain's authorized sending sources. They recommend updating the SPF record to include Exclaimer's sending servers to resolve this issue.
25 Aug 2023 - Exclaimer.com
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