Summary
AMP emails going to spam in Outlook can stem from a multitude of factors. Given Outlook's lack of native AMP support, the quality and proper configuration of the HTML fallback are paramount. General deliverability best practices, such as strong sender reputation, correct email authentication (SPF, DKIM, DMARC), and engaging content, are essential. Specific technical issues involving MIME configurations, security compliance with AMP specifications, and triggering Outlook's SmartScreen Filter can also cause deliverability problems. Gradual IP warming, using feedback loops, thorough testing across email clients (including Outlook), and educating users to add senders to their Safe Senders lists are recommended strategies for improved deliverability.
Key findings
- Fallback Importance: Since Outlook doesn't support AMP, a well-coded and functional HTML fallback is crucial to avoid spam filters.
- Sender Reputation Matters: A good sender reputation (IP and domain) is critical for reaching the inbox in Outlook. Past spam complaints or blacklisting can severely impact deliverability.
- Email Authentication is Key: Properly implementing SPF, DKIM, and DMARC is crucial for verifying the legitimacy of your emails and preventing them from being marked as spam.
- Content is King: The content of your email can trigger spam filters if it contains spam trigger words, URL shorteners, or other suspicious elements.
- Technical Compliance: Correct MIME configurations, adherence to AMP specifications, and avoiding elements that trigger Outlook's SmartScreen Filter are all vital for proper deliverability.
Key considerations
- Optimize the HTML Fallback: Ensure the HTML fallback is a fully functional and visually appealing version of your AMP email.
- Improve Sender Reputation: Warm up your IP address gradually, maintain consistent sending volumes, and encourage user engagement to build a positive sender reputation.
- Implement Email Authentication: Implement SPF, DKIM, and DMARC to verify your sending domain and protect your emails from spoofing.
- Review Email Content: Avoid using spam trigger words, URL shorteners, or any content that might raise red flags with spam filters.
- Test Thoroughly: Use email testing tools like Litmus to preview your emails in Outlook and identify any potential deliverability issues before sending.
- Setup Feedback Loops: Use FBL (Feedback Loop) mechanisms to monitor your reputation.
- User Education: Encourage users to add your sending address to their safe sender list in Outlook, but understand that this is not a foolproof solution.
What email marketers say
10 marketer opinions
AMP emails may land in Outlook's spam folder due to a variety of factors. Key issues include problems with the HTML fallback version, sender reputation, email authentication (SPF, DKIM, DMARC), email content triggering spam filters, and improper MIME configurations. Consistent sending volume, engaging content, IP warm-up, and feedback loops can improve deliverability. Thorough testing across different email clients, including Outlook, is crucial. Email headers should be reviewed for unexpected changes.
Key opinions
- Fallback Issues: Incorrectly configured or non-functional HTML fallback versions for AMP emails can lead to spam filtering in Outlook.
- Sender Reputation: A poor sender reputation (due to low IP warm-up or past spam complaints) significantly increases the likelihood of emails going to spam.
- Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) makes emails appear less trustworthy, leading to spam filters.
- Content Triggers: Certain content elements (spam trigger words, URL shorteners) can flag emails as spam.
- Testing is Crucial: Thoroughly testing AMP emails across different email clients like Outlook can ensure proper rendering and identify spam triggers.
Key considerations
- Check Fallback: Ensure your HTML fallback version is functional and follows email best practices to provide a usable email even if AMP isn't supported.
- Improve Reputation: Warm up your IP address gradually, maintain consistent sending volumes, and ensure recipients engage with your emails to build a positive sender reputation.
- Implement Authentication: Properly configure SPF, DKIM, and DMARC to authenticate your emails and signal to email providers that your emails are legitimate.
- Review Content: Avoid using spam trigger words, URL shorteners, or other elements that may cause your emails to be flagged as spam.
- Monitor Headers: Examine email headers in the inbox to identify any unexpected changes or flags that might be causing spam filtering.
- Use Feedback Loops: Setup feedback loops with Microsoft to receive reports when users mark your emails as spam, allowing you to address issues promptly.
Marketer view
Email marketer from Mailjet explains that several factors can affect whether emails land in Outlook's spam folder, including sender reputation, email content, and authentication.
7 Jan 2024 - Mailjet
Marketer view
Marketer from Email Geeks suggests looking at the email headers in the inbox to see if anything is getting changed as a place to start troubleshooting.
3 Jun 2023 - Email Geeks
What the experts say
3 expert opinions
AMP emails may be directed to spam in Outlook due to the fact that Outlook doesn't support AMP, relying instead on the HTML fallback. A poorly coded or non-functional fallback can trigger spam filters. Additionally, a negative sender reputation stemming from past spam complaints or blacklisting can significantly impact deliverability to Outlook, causing even properly formatted emails to land in the spam folder.
Key opinions
- Outlook Fallback: Outlook relies on the HTML fallback of AMP emails, as it does not natively support AMP.
- Fallback Quality: The quality and functionality of the HTML fallback are crucial; a poorly coded fallback can trigger spam filters.
- Sender Reputation: A poor sender reputation, stemming from past spam complaints or blacklisting, negatively impacts deliverability to Outlook.
Key considerations
- Optimize Fallback: Prioritize a well-coded, fully functional HTML fallback to ensure proper rendering in Outlook and avoid spam filters.
- Monitor Reputation: Actively monitor and maintain a positive sender reputation by avoiding practices that lead to spam complaints or blacklisting.
Expert view
Expert from Email Geeks explains that AMP doesn’t work at Outlook so they should always get the fall back anyway. Probably safe to I get the tests failing there.
16 May 2024 - Email Geeks
Expert view
Expert from Word to the Wise explains that because not all email clients support AMP, having a well-coded HTML fallback version is vital. Outlook, in particular, relies on the HTML fallback. Ensure this version is fully functional and adheres to best practices to avoid spam filters.
9 Apr 2025 - Word to the Wise
What the documentation says
5 technical articles
AMP emails may be filtered as spam in Outlook due to several technical factors outlined in official documentation. Outlook's SmartScreen Filter can flag AMP emails if they trigger its spam detection mechanisms. AMP emails also have strict security requirements, including valid SSL certificates and adherence to AMP specifications; non-compliance can lead to deliverability problems. Correct MIME part configurations are crucial for proper rendering and avoiding spam issues. Tools like Litmus can help test AMP email deliverability and identify potential spam triggers before sending. Users can add senders to their Safe Senders list, but this is not a guaranteed solution for all recipients.
Key findings
- SmartScreen Filter: Outlook's SmartScreen Filter may flag AMP emails as spam if they meet certain criteria.
- Security Requirements: AMP emails have strict security requirements; non-compliance can cause deliverability issues.
- MIME Configuration: Incorrect MIME configurations in AMP emails can lead to rendering problems and spam detection.
- Testing Importance: Testing AMP emails with tools like Litmus can help identify and resolve potential spam triggers.
- Safe Senders List: Users can add senders to their Safe Senders list in Outlook, but this is not a comprehensive solution.
Key considerations
- Address Filter Triggers: Identify and address any elements in your AMP email that might trigger Outlook's SmartScreen Filter.
- Ensure Security Compliance: Verify that your AMP emails meet all security requirements, including valid SSL certificates and adherence to AMP specifications.
- Check MIME Structure: Ensure that the MIME part configurations of your AMP emails are correct, including the proper structure for AMP and fallback versions.
- Utilize Testing Tools: Use tools like Litmus to test your AMP emails for deliverability and spam triggers before sending.
- Educate Recipients: Encourage recipients to add your address to their Safe Senders list, but understand this doesn't guarantee deliverability for everyone.
Technical article
Documentation from RFC-Editor.org details the correct MIME part configurations for emails, including the proper structure for including AMP and fallback versions. Incorrect MIME structure might cause rendering and spam issues.
29 Apr 2025 - RFC-Editor.org
Technical article
Documentation from Microsoft Support explains that users can add senders to their safe sender list in Outlook, which can help ensure that emails from those senders are not marked as spam. However, this is a user-specific setting and does not guarantee deliverability for all users.
14 Aug 2022 - Microsoft Support
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