Summary
Emails being flagged as phishing and failing to deliver in Outlook are multifaceted issues stemming from sender reputation, email content, authentication failures, and list management practices. Compromised tracking pixels, suspicious email content, shared IP usage, and poor list hygiene negatively affect sender reputation and trigger spam filters. Inadequate or absent email authentication (SPF, DKIM, DMARC) allows spoofing and raises suspicion. Proactive measures such as content optimization, implementing robust authentication, monitoring sender reputation, and maintaining clean email lists are critical for enhancing deliverability and avoiding phishing flags.
Key findings
- Compromised Pixels: Tracking pixels, especially deprecated ones or those hosted on shared domains, can be flagged as 'PHISH' by Microsoft, impacting deliverability.
- Content Triggers: Suspicious links, misleading language, and spammy keywords in email content can trigger spam filters.
- Shared IP Risks: Using a shared IP address exposes your emails to the reputation of other senders on that IP, potentially leading to deliverability issues.
- Authentication Gaps: Lacking proper SPF, DKIM, and DMARC authentication allows spoofing and increases the likelihood of being flagged as spam or phishing.
- Poor List Hygiene: Sending to spam traps, invalid addresses, or unengaged recipients damages sender reputation and increases the chance of being flagged.
- Reputation Matters: Outlook uses a sender reputation system, where a poor reputation significantly increases the likelihood of emails being filtered or blocked.
- Blocklist Impact: Being listed on a blocklist indicates that your IP address or domain has been associated with spam activity, severely impacting deliverability.
- Volume Spikes: A sudden surge in email sending volume can trigger spam filters and negatively affect deliverability.
Key considerations
- Audit Tracking Pixels: Regularly audit and remove deprecated or potentially compromised tracking pixels.
- Optimize Email Content: Carefully review email content to avoid suspicious links, misleading language, and spam trigger words.
- Evaluate IP Strategy: Consider using a dedicated IP address or monitoring shared IP reputation to mitigate risks.
- Implement Strong Authentication: Ensure proper configuration of SPF, DKIM, and DMARC to authenticate your emails and improve deliverability.
- Maintain Clean Lists: Regularly clean your email list to remove invalid addresses, spam traps, and unengaged recipients, and use an email list validation service.
- Monitor Reputation: Proactively monitor your sender reputation and address any negative signals promptly.
- Review Blocklist Status: Periodically check if your IP address or domain is listed on any blocklists and take steps to be removed if necessary.
- Monitor feedback loops: Set up feedback loops with email providers to identify issues that cause your emails to be flagged as spam.
- Control Sending Volume: Gradually increase your sending volume to establish a consistent sending reputation and avoid triggering spam filters.
What email marketers say
12 marketer opinions
Emails failing to deliver to Outlook and being flagged as phishing can stem from various factors related to sender reputation, email content, authentication, and list management. Deprecated tracking pixels, suspicious content, shared IP issues, and poor list hygiene can all contribute to the problem. Proper email authentication (SPF, DKIM, DMARC), maintaining a clean email list, and avoiding spam triggers are crucial for improving deliverability.
Key opinions
- Tracking Pixels: Deprecated or compromised tracking pixels can be flagged as 'PHISH' by Microsoft Outlook, impacting deliverability.
- Content Issues: Suspicious links, misleading language, or certain keywords in email content can trigger spam filters.
- Shared IPs: Using a shared IP address can negatively impact deliverability if other users on the same IP engage in spammy practices.
- Authentication: Lack of proper email authentication (SPF, DKIM, DMARC) can lead to emails being flagged as spam.
- List Hygiene: Sending emails to spam traps or unengaged recipients can damage sender reputation and result in deliverability issues.
- Sudden Volume Increase: A sudden increase in email sending volume can trigger spam filters.
- Misleading Subject Lines: Deceptive or misleading subject lines can cause email to be flagged as spam.
- Low domain reputation: A low domain reputation can cause emails to be flagged as spam.
Key considerations
- Review Tracking Pixels: Regularly audit and remove deprecated or potentially compromised tracking pixels.
- Optimize Email Content: Carefully review email content to avoid suspicious links, misleading language, and spam trigger words.
- IP Reputation: Consider using a dedicated IP address or monitoring shared IP reputation.
- Implement Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) is in place.
- Maintain List Hygiene: Regularly clean your email list to remove inactive or invalid addresses, and use an email list validation service.
- Manage Sending Volume: Gradually increase sending volume to establish a consistent sending reputation.
- Monitor Feedback Loops: Set up feedback loops with email providers like Outlook to identify and address issues.
- Subject Line Content: Ensure your subject lines accurately reflect the content of your email
Marketer view
Email marketer from Reddit shares that if your emails are being classified as phishing, it could be due to suspicious links or wording in the email content. Avoid using URL shorteners or language commonly associated with phishing scams.
8 Oct 2024 - Reddit
Marketer view
Email marketer from Email Geeks shares that a tracking pixel was being flagged by Microsoft as 'PHISH'. After removing the pixel, test emails started coming through. The pixel was for a deprecated product called Display, hosted on the <http://adnxs.com|adnxs.com> domain.
15 Sep 2024 - Email Geeks
What the experts say
6 expert opinions
Emails being flagged as phishing and not delivering to Outlook are often due to a combination of factors. These include compromised tracking pixels, shared hosting with potentially malicious actors, poor sender reputation stemming from spam complaints and list hygiene issues, suspicious content within the emails, and a lack of proper email authentication (SPF, DKIM, DMARC). Addressing these issues through careful monitoring, content optimization, and implementing authentication protocols is crucial for improving deliverability.
Key opinions
- Phishing Flags and Pixels: If a tracking pixel is flagged as 'PHISH', investigate if a phishing site is being hosted or if the pixel's domain is shared with a compromised entity.
- Shared Hosting Risks: Using a third-party domain for tracking pixels means sharing reputation and delivery with all other customers of that provider.
- Sender Reputation Impact: Poor sender reputation, built from spam complaints, bounce rates, and authentication issues, leads to emails being flagged.
- Content as a Trigger: Suspicious links and language in email content can cause emails to be misidentified as phishing attempts.
- Authentication Importance: Lack of SPF, DKIM, and DMARC authentication makes it easier for emails to be spoofed, leading to spam or phishing flags.
- List Hygiene Consequences: Sending to spam traps and unengaged recipients lowers sender reputation, increasing the chances of being flagged.
Key considerations
- Investigate Phishing Flags: When emails are flagged as phishing, thoroughly investigate the email content and any associated tracking pixels for suspicious activity.
- Evaluate Shared Resources: Be aware of the risks associated with sharing hosting or tracking pixel domains with third parties.
- Monitor Sender Reputation: Regularly monitor sender reputation and address any negative signals promptly.
- Optimize Email Content: Avoid suspicious links and language that could trigger phishing filters.
- Implement Email Authentication: Set up SPF, DKIM, and DMARC to verify email authenticity and improve deliverability.
- Practice List Hygiene: Maintain a clean email list by removing inactive addresses and avoiding spam traps.
Expert view
Expert from Spam Resource explains that a poor sender reputation is a primary reason for deliverability issues, leading to emails being flagged as spam or phishing. Sender reputation is built over time and is based on factors such as spam complaints, bounce rates, and email authentication practices.
26 Apr 2024 - Spam Resource
Expert view
Expert from Word to the Wise explains that proper email authentication (SPF, DKIM, DMARC) is critical for ensuring deliverability. These protocols help verify that the email is genuinely from the sender and not a spoofed address, reducing the likelihood of being flagged as spam or phishing.
21 Sep 2024 - Word to the Wise
What the documentation says
5 technical articles
Emails failing to deliver to Outlook and being flagged as phishing are often caused by issues relating to sender reputation, email authentication, and blacklisting. Microsoft's documentation highlights the influence of blocklists, spam filters, and proper authentication (SPF, DKIM, DMARC). DMARC.org emphasizes DMARC's role in preventing spoofing and improving deliverability. Spamhaus provides a way to check if an IP or domain is blocklisted. The RFC standard defines SPF as an email authentication method to prevent domain spoofing.
Key findings
- Blocklist Status: Being listed on a Spamhaus blocklist indicates association with spam activity and impacts deliverability.
- Sender Reputation: Outlook uses a sender reputation system; poor reputation leads to emails being filtered or blocked.
- Authentication Protocols: Lack of proper SPF, DKIM, and DMARC authentication contributes to deliverability issues and potential phishing flags.
- Multiple Factors: Several factors can lead to junk folder placement, including IP address on blocklists, spam filters, and user-defined rules.
- DMARC Impact: Implementing DMARC can significantly improve email deliverability by preventing spoofing and phishing attacks.
Key considerations
- Check Blocklist Status: Use tools like Spamhaus's blocklist lookup to see if your IP address is listed.
- Improve Sender Reputation: Monitor and improve sender reputation by addressing spam complaints and bounce rates.
- Implement Authentication: Ensure proper configuration of SPF, DKIM, and DMARC to authenticate your emails.
- Review Email Content: Review email content to avoid triggering spam filters.
- Implement DMARC: Implement DMARC to protect your domain from email spoofing.
Technical article
Documentation from DMARC.org explains that DMARC (Domain-based Message Authentication, Reporting & Conformance) is an email authentication protocol that helps prevent email spoofing and phishing attacks. Implementing DMARC can significantly improve email deliverability to Outlook and other providers.
11 Sep 2024 - DMARC.org
Technical article
Documentation from RFC standard explains that SPF (Sender Policy Framework) is an email authentication method used to prevent spammers from sending messages on behalf of your domain. An SPF record identifies which mail servers are authorized to send email for your domain.
4 Jul 2024 - RFC Editor
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