How to troubleshoot blocked images and warnings in promotional emails on Google Workspace?
Matthew Whittaker
Co-founder & CTO, Suped
Published 29 Apr 2025
Updated 19 Aug 2025
9 min read
Dealing with blocked images and warning banners in promotional emails on Google Workspace can be a frustrating experience. It affects not only the visual appeal of your campaigns but also their overall effectiveness and how your subscribers perceive your brand. When emails display warnings like "Images are hidden, this message might be suspicious" or "Be careful with this message," it immediately raises red flags for recipients and impacts your sender reputation.
These issues often stem from Google's robust security measures, designed to protect users from spam and phishing attempts. While beneficial for recipients, they can inadvertently catch legitimate promotional emails. Understanding the underlying causes, from authentication failures to content issues, is the first step toward effective troubleshooting and ensuring your messages reach the inbox as intended, with all images displayed correctly.
Understanding Google’s filtering mechanisms
When Google Workspace blocks images or flags an email with a warning, it's usually an indicator that something has triggered its spam filters or security protocols. These systems analyze various factors, including sender reputation, authentication records, and email content, to assess the trustworthiness of incoming messages. A common warning, for example, is the "Images in this email are hidden" banner, which indicates Google suspects the email might be suspicious. You can learn more about how this message affects email marketing and how it relates to deliverability.
One of the primary reasons for these issues is a poor sender reputation. Google maintains a sophisticated system to track and assign a reputation score to sending domains and IP addresses. If your domain or the IP address used by your email service provider (ESP) has a history of sending spam, hitting spam traps, or generating a high complaint rate, Google Workspace is more likely to block your content. This can manifest as emails going directly to the spam folder, or specific elements like images being blocked in the inbox.
Another critical factor is email authentication. Google strongly recommends implementing SPF, DKIM, and DMARC. These protocols help verify that your emails are legitimate and prevent spoofing. Missing or incorrectly configured records for these standards can significantly impact your email deliverability, leading to images being hidden or emails being flagged. You can consult a simple guide to DMARC, SPF, and DKIM to ensure these are set up correctly.
Google Workspace sender guidelines
Authentication standards: Ensure all your sending domains have valid SPF, DKIM, and DMARC records set up. These records help Gmail verify your sender identity and reduce the likelihood of your emails being marked as suspicious. You can find email sender guidelines from Google Workspace directly.
Sender reputation: Consistently monitor your domain and IP reputation using tools like Google Postmaster Tools. A good reputation indicates to Google that you are a trustworthy sender.
Content quality: Avoid using excessive images, suspicious links, or content commonly associated with spam. Ensure a healthy text-to-image ratio.
Common triggers for image blocking and warnings
Beyond authentication and general sender reputation, specific content and linking practices can trigger image blocking and warnings. Google's algorithms are constantly evolving, and what might have worked previously may now be flagged. Promotional emails, by their nature, often contain more images and links, making them more susceptible to these filters.
One common pitfall is a high image-to-text ratio, or worse, image-only emails. While visually appealing, emails with very little text and many large images can be perceived as spam by Google's filters, as spammers often use images to bypass text-based content analysis. Similarly, hidden content using CSS or HTML can trigger warnings, as this is a technique spammers use to conceal malicious links or keywords. If you're using image-only emails, protect your deliverability by ensuring proper authentication and good sender practices.
Links within your email also play a significant role. Broken links, redirects to suspicious domains, or the use of public URL shorteners can all trigger security warnings. Google's Safe Browsing technology flags domains known for malware or phishing. If your email contains links to such domains, even inadvertently, Google Safe Browsing can mark your domain unsafe, leading to prominent warnings. Additionally, linking directly to a login page without any preceding content has been observed to trigger warnings, as this can sometimes be a characteristic of phishing attempts. You can read more about why emails get a phishing warning in Gmail to further understand this behavior.
Content pitfalls
Image-heavy emails: Sending emails with a disproportionate number of images compared to text, or emails that are entirely image-based, can be flagged as suspicious by spam filters.
Hidden content: Using CSS or HTML to conceal text or links can trigger warnings because it's a tactic often employed by spammers.
Broken or suspicious links: Emails containing broken links, redirects, or links to domains flagged for malware or phishing can result in warnings or blocks.
Beyond content, other factors can influence Google's decision to block images or display warnings. These include: inconsistent sending volume, a sudden spike in email volume from a previously low-volume sender, or a high bounce rate indicating poor list hygiene. All these elements contribute to your overall sender reputation and can lead to images being hidden.
Technical configurations and domain reputation
The technical setup of your email sending infrastructure is foundational to deliverability. Without proper authentication, your emails lack the necessary trust signals for Google Workspace to deliver them reliably. SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) are essential DNS records that verify your emails are indeed from your domain and haven't been tampered with.
An SPF record specifies which mail servers are authorized to send emails on behalf of your domain. DKIM adds a digital signature to your outgoing emails, allowing the recipient's server to verify that the email was not altered in transit. DMARC builds upon SPF and DKIM, providing instructions to receiving mail servers on how to handle emails that fail authentication (e.g., quarantine or reject) and offers reporting capabilities to monitor your domain's email activity. Proper configuration of these records is vital to fix common DMARC issues that can affect both Microsoft 365 and Google Workspace.
Beyond these, monitoring your domain's reputation with Google Postmaster Tools is essential. This free service provides detailed insights into your sender reputation, spam rate, IP reputation, and DMARC, SPF, and DKIM authentication statuses. A low domain reputation or high spam rate, even if your authentication records are perfect, can lead to images being blocked or emails landing in the spam folder.
If you're using a third-party email service provider (ESP) for your promotional emails, ensure their sending IPs are reputable and properly warmed up. Shared IPs, while cost-effective, can sometimes be impacted by other senders' poor practices, leading to your emails being affected. Dedicated IPs offer more control but require careful management of your own sending volume and reputation.
Actionable steps for troubleshooting and prevention
When encountering blocked images or warnings, a systematic troubleshooting approach is key. Start by verifying your email authentication. Use online tools to check your SPF, DKIM, and DMARC records for errors. Even a small misconfiguration can cause significant deliverability issues. Ensure your SPF record includes all authorized sending sources, including your ESP.
Next, examine your email content. Reduce the image-to-text ratio, ensure images have descriptive alt text (this also helps with accessibility), and avoid any hidden text or links. Review all links in your email to ensure they are reputable and functional. If you are linking to a sensitive page like a login portal, ensure there's sufficient content on the landing page beyond just the login form. Consider reducing the number of links if your emails are heavily linked, as too many links can be a spam trigger. You can find tips to prevent emails from going to spam more broadly.
Actively monitor your sender reputation using Google Postmaster Tools. Pay close attention to your spam rate and any DMARC failures. A high spam complaint rate is a strong signal to Google that your emails are not desired by recipients, which can quickly lead to blocklistings (or blacklistings) and warnings. If your domain is indeed on a blocklist, understanding what happens when your domain is on an email blacklist is crucial for recovery. For images, ensuring they meet Google's quality filters (e.g., proper dimensions and clear content) is also important. Images must pass Google’s quality filter to display in the inbox without issues. Finally, consider performing a full email deliverability test regularly.
Troubleshooting checklist
Verify authentication: Confirm SPF, DKIM, and DMARC records are correctly configured and aligned.
Check content ratio: Ensure a balanced text-to-image ratio and avoid hidden content.
Inspect links: Verify all links are functional, secure (HTTPS), and not flagged by Google Safe Browsing.
Monitor reputation: Use Google Postmaster Tools for ongoing domain and IP reputation tracking.
Test thoroughly: Send test emails to various accounts, including a Gmail account, to observe inbox placement and image rendering.
Views from the trenches
Views from the trenches
Best practices
Always include alt text for all images in your promotional emails. This ensures that even if images are blocked, recipients still understand the content.
Maintain a healthy text-to-image ratio. Avoid sending emails that are purely images; balance visuals with descriptive text.
Regularly monitor your domain's reputation using Google Postmaster Tools and address any negative trends promptly.
Implement and correctly configure SPF, DKIM, and DMARC for all sending domains to build sender trust.
Segment your email lists and personalize content to improve engagement and reduce spam complaints.
Common pitfalls
Sending emails with a large percentage of images and very little text, which can trigger spam filters.
Using public URL shorteners or suspicious-looking links that can be flagged by Google Safe Browsing.
Ignoring DMARC reports, which contain crucial information about authentication failures and potential spoofing attempts.
Linking directly to a login page without any contextual content on the landing page, which can appear suspicious.
Not whitelisting your legitimate sending domains within Google Workspace for internal communications.
Expert tips
If images are blocked specifically for internal recipients, check your Google Workspace admin console for internal mail routing rules or security settings that might be overzealous.
When troubleshooting, isolate variables: send test emails with only text, then gradually add images and links to pinpoint the exact trigger.
Ensure your email service provider (ESP) has a good sending reputation, especially if you are using shared IP addresses, as their reputation impacts yours.
For promotional emails, focus on building strong recipient engagement, as positive interactions signal trustworthiness to Google's algorithms.
Educate your internal team on how to mark legitimate emails as 'not spam' to improve your internal deliverability reputation.
Expert view
Expert from Email Geeks says to verify the domain or any links included in the email are not listed in Google Web Risk. Often, if other emails without links deliver fine, a flagged domain inside the email is the culprit.
2025-03-13 - Email Geeks
Expert view
Expert from Email Geeks says the most appropriate action when encountering these issues is to contact the Google Workspace admin, not solely the email service provider (ESP), as internal settings might be at play.
2025-03-13 - Email Geeks
The path to clear inboxes
Troubleshooting blocked images and warnings in promotional emails on Google Workspace requires a multi-faceted approach, addressing both technical configurations and content best practices. By focusing on robust email authentication, maintaining a stellar sender reputation, and crafting engaging, trustworthy content, you can significantly improve your email deliverability.
Regular monitoring with tools like Google Postmaster Tools and proactive testing are vital to catch issues before they escalate. Remember, Google's primary goal is to protect its users, so aligning your sending practices with their guidelines will always lead to better inbox placement and full display of your promotional content. Consistent effort in these areas will ensure your messages are delivered effectively, allowing your images to shine and your warnings to disappear.
Google Workspace can be a frustrating experience. It affects not only the visual appeal of your campaigns but also their overall effectiveness and how your subscribers perceive your brand. When emails display warnings like "Images are hidden, this message might be suspicious" or "Be careful with this message," it immediately raises red flags for recipients and impacts your sender reputation.
Microsoft 365 and Google Workspace.
Google Postmaster Tools for ongoing domain and IP reputation tracking.
