Why are emails not being delivered when I include my email signature?
Summary
What email marketers say9Marketer opinions
Email marketer from Mailchimp Resource Center explains that large image files in your email signature can increase the email's overall size, potentially causing it to be flagged as spam or rejected by some email servers. Optimize images to reduce file size without sacrificing quality.
Email marketer from Email on Acid shares that using URL shorteners (like bit.ly) in your email signature can negatively impact deliverability. Spam filters often flag shortened URLs as suspicious because they can mask the true destination of the link.
Email marketer from StackExchange shares that including a phone number in your signature may lead to deliverability problems if the phone number is associated with spam activity or if it is formatted in a way that looks suspicious to spam filters. For example excessive spacing between the numbers.
Email marketer from Tech Support Forum explains that hosting images for your email signature on unreliable or blacklisted servers can cause your emails to be blocked. Ensure your images are hosted on reputable platforms.
Email marketer from Reddit shares that links within your signature, especially to newly registered or low-reputation domains, can trigger spam filters. Services may see it as suspicious if the domain is flagged. Suggests monitoring domain reputation using online tools.
Email marketer from Litmus shares that having a signature with an excessive amount of images compared to text can lead to deliverability issues. Maintain a healthy text-to-image ratio.
Email marketer from Gmass explains that missing or misleading alt text for images in your signature can raise red flags with spam filters. Provide descriptive and relevant alt text for all images.
Email marketer from Email Geeks suggests that the HTML code in the signature might be the issue, recommending rewriting it with simple HTML.
Email marketer from HubSpot Blog shares that certain words in your signature, especially those related to sales, finance, or health, can trigger spam filters. Avoid using overly promotional or suspicious language.
What the experts say5Expert opinions
Expert from Email Geeks suspects the destination URL (<http://addictivedesign.ca|addictivedesign.ca>) in the signature might have a bad reputation, causing delivery issues.
Expert from Email Geeks recommends removing elements from the signature one at a time to identify the problematic element, suggesting the logo's host, URLs, or social tags could be the issue.
Expert from Spam Resource (Laura Atkins) explains that overly complex HTML in email signatures, especially when combined with large images or unusual fonts, can contribute to deliverability problems. Simplifying the signature design and using web-safe fonts can help.
Expert from Word to the Wise Staff explains that using excessive tracking parameters on links within an email signature can raise suspicion with spam filters. It's important to use tracking judiciously and ensure it doesn't make links appear overly complex or malicious.
Expert from Email Geeks suggests to redo the signature without the phone number and domain, test, and then add back one at a time to isolate the issue.
What the documentation says5Technical articles
Documentation from Microsoft Support explains that if the recipient has accidentally added the sender's email address or domain to their blocked sender list in Outlook, emails, including those with signatures, will be automatically moved to the Junk Email folder or rejected outright.
Documentation from RFC Editor specifies that non-compliant HTML code in email signatures can cause rendering issues or trigger spam filters. Ensure your signature code adheres to email standards (e.g., avoiding excessive use of CSS or JavaScript).
Documentation from Google Workspace Admin Help explains that if your domain's SPF, DKIM, and DMARC records are not properly configured, email servers may reject emails originating from your domain, especially those with signatures containing links or images. Properly configuring these authentication methods increases deliverability.
Documentation from DKIM.org explains that a correctly formatted DKIM record is crucial for email authentication. Incorrect syntax, key size, or other errors in your DKIM record can cause email delivery failures, especially when signatures are involved. Use a DKIM validator to ensure the record is correct.
Documentation from SPF-Record.com highlights that SPF records have a lookup limit of 10. If your SPF record exceeds this limit due to including too many 'include:' mechanisms (often caused by third-party services), it can cause SPF checks to fail, leading to emails being rejected, especially when signatures are added.