How do spam filters evaluate emails with signatures?
Most spam filter issues are caused by overall email content, server reputation, or recipient filter configurations rather than your email signature itself. In fact, a professional company email signature generally helps establish legitimacy because spammers rarely use structured business signatures.
Spam scoring: Spam filters evaluate multiple factors - including your email server, subject line, body text, links, images, and signature - to calculate an overall spam score. If that score exceeds a server's threshold, the message is routed to the junk folder.
Server-specific rules: Individual server administrators configure spam filters differently. An email that passes one company's spam filter may be flagged by another company using different threshold settings.
Adaptive filtering: Email providers continuously update their spam criteria based on user actions, such as recipients clicking Mark as spam or This is junk.
How can I prevent my email signature from triggering spam filters?
To reduce the risk of your emails being flagged as spam when using a MySignature email signature, follow these six best practices:
1. Maintain a healthy text-to-image ratio
Emails with large graphics and very little written text frequently trigger spam filters. Aim for an 80:20 text-to-image ratio in your overall email (a 60:40 text-to-image ratio is typically sufficient) so your message contains more text than images.
2. Link only to standard web pages
Avoid linking to URLs that lead directly to a .php page in your email signature or message body, as URL paths pointing to PHP pages are consistently flagged as spam.
3. Keep the total number of links below 6
Spam filters often flag emails containing a high volume of hyperlinks. Keep the number of links in your MySignature email signature below 6 - including 5 or fewer links is generally safe for deliverability.
4. Check skin-tone color ratios in photos and banners
Many spam filters analyze the proportion of skin-tone pixels in images to block explicit content. If your MySignature email signature includes a headshot photo or promotional banner with a high concentration of skin-tone colors, test your signature with a small group of pilot recipients to verify that it passes their spam filters.
5. Use MySignature-hosted image paths
Use images hosted directly through MySignature to help prevent image URLs from triggering spam filters. Only host signature images on your own server if your recipient's organization has specifically whitelisted your domain.
6. Replace default mobile signatures
While default mobile disclaimers such as "Sent from iPhone" rarely trigger automated spam filters, recipients may perceive them as unprofessional or treat them as junk. Install your unified MySignature email signature across all desktop and mobile email clients for consistent branding.
How do I test my email signature for spam issues?
If your emails continue landing in spam and you want to isolate whether an element in your MySignature email signature is contributing to the issue, follow these testing steps:
Send a plain test email without your signature to the same recipient to confirm whether the issue is caused by your email server or domain reputation.
Add your MySignature elements back one at a time - such as text first, then links, then your logo or banner - and send a test email after each addition to identify which element triggers the filter.
Send test messages to multiple email providers and from different IP addresses to verify whether the block is isolated to a single recipient's server.
Ask the recipient to check their personal blocklist, especially on mobile mail apps, as accidentally blocking a sender on a mobile app can also cause messages to route to spam on their desktop email client.
Need more help?
If you have other questions about email deliverability or signature setup, check our Knowledge Base for more articles, or contact our Support Team via live chat or email.