Summary
Microsoft email bounces stem from various factors including EC2/SES blocking, aggressive throttling, poor IP reputation, authentication failures (SPF, DKIM, DMARC), list hygiene issues, content triggering spam filters, sending volume spikes, and potential neighbor issues. Addressing these problems requires a multifaceted approach: review bounce messages, investigate sending practices, implement custom rDNS, maintain consistent volume with gradual IP warm-up, monitor SNDS and enroll in JMRP for feedback, improve email authentication, clean email lists, optimize content, segment emails for better engagement, and manage sending volume carefully.
Key findings
- EC2/SES Blocking: Microsoft may block emails originating from EC2 or SES infrastructure.
- Aggressive Throttling: Hotmail/Outlook is known for aggressive throttling, especially affecting new IPs or sudden volume increases.
- Poor IP Reputation: A low IP reputation, stemming from blocklisting or negative sender behavior, significantly impacts deliverability.
- Authentication Failures: Failure to properly implement SPF, DKIM, and DMARC records can result in emails being rejected or marked as spam.
- List Hygiene Problems: Sending to inactive or invalid email addresses damages sender reputation and increases bounce rates.
- Spam Filter Triggers: Email content that contains overly promotional language, lacks an unsubscribe option, or triggers spam filters leads to deliverability issues.
- Volume Spikes: Sudden increases in email sending volume can be flagged as suspicious and result in throttling or blocking.
- Shared IP Issues: Deliverability can be negatively impacted if using a shared IP due to the sending habits of others.
Key considerations
- Review Bounce Messages: Carefully examine bounce messages and NDR codes to identify specific reasons for email delivery failures.
- Investigate Sending Practices: Analyze sending practices, particularly for new customers, to identify potential issues.
- Implement Custom rDNS: Consider implementing custom reverse DNS to better manage IP reputation.
- Maintain Consistent Volume: Maintain a consistent sending volume, and gradually warm up new IPs to establish trust.
- Monitor SNDS: Use Microsoft's SNDS to actively monitor IP reputation and identify deliverability issues.
- Enroll in JMRP: Enroll in Microsoft's JMRP to receive feedback on spam complaints and address any underlying problems.
- Improve Email Authentication: Implement and verify correct configuration of SPF, DKIM, and DMARC records.
- Clean Email Lists: Regularly remove inactive or invalid email addresses to maintain a healthy list and improve deliverability.
- Optimize Content: Ensure emails avoid spam trigger words and contain a clear and easy unsubscribe process.
- Segment Emails: Segment email lists and personalize content to improve engagement and reduce bounces.
- Control Sending Volume: Avoid sudden spikes in sending volume, and gradually increase the amount of email sent.
- Contact MS Support: Consider contacting MS deliverability support to allow mitigation for the IP and setup appropriate throttle on outbound IP.
What email marketers say
11 marketer opinions
Microsoft email address bounces often stem from IP reputation, content triggering spam filters, and sudden sending volume spikes. Solutions include warming up IPs, email authentication (SPF, DKIM, DMARC), list cleaning, content review, sender reputation monitoring using SNDS/JMRP, personalized segmentation, and gradual volume increases.
Key opinions
- IP Reputation: Poor IP reputation due to blocklisting or shared IP neighbors significantly impacts Microsoft deliverability.
- Email Authentication: Lack of proper SPF, DKIM, and DMARC configuration leads to deliverability issues.
- List Hygiene: Sending to inactive or invalid email addresses degrades sender reputation and increases bounce rates.
- Spam Filtering: Email content with promotional language or lacking a clear unsubscribe process triggers Microsoft's spam filters.
- Sending Volume: Sudden increases in email volume can be flagged as suspicious, leading to throttling or blocking.
- Engagement: Low user engagement with email can lead to deliverability issues.
Key considerations
- Warm-up IP: Gradually warm up new IPs to establish a positive sending reputation with Microsoft.
- Implement Authentication: Ensure SPF, DKIM, and DMARC are correctly configured for your sending domain.
- Clean Email List: Regularly remove inactive or invalid email addresses from your mailing lists.
- Review Content: Avoid overly promotional language and provide a clear and easy unsubscribe process.
- Monitor SNDS: Use Microsoft's SNDS to monitor your IP reputation and identify deliverability issues.
- Segment Emails: Targeted and personalized emails lead to higher user engagement and fewer bounces.
- Gradual Volume Increase: Ramp up email volume gradually to avoid triggering spam filters.
- Custom Tracking Domain: Use a custom tracking domain for cold emails
Marketer view
Email marketer from DigitalMarketer explains that to improve email deliverability, focus on segmentation and personalization. Sending relevant content to specific segments of your audience can improve engagement and reduce bounce rates. Avoid sending the same generic email to your entire list.
20 Feb 2022 - DigitalMarketer
Marketer view
Email marketer from EmailOversight shares that issues with Microsoft email addresses often stem from reputation issues. They recommend using Microsoft's JMRP program to receive feedback on spam complaints, ensuring your sending IPs aren't on blocklists, and proactively managing your sender reputation.
2 Aug 2023 - EmailOversight
What the experts say
5 expert opinions
Microsoft email bounces are often caused by sending from EC2/SES, aggressive throttling, poor IP reputation, and neighbor issues. Address these by reviewing bounce messages, investigating customer sending practices, using custom reverse DNS, maintaining consistent volume, monitoring SNDS, enrolling in JMRP, and addressing complaints promptly.
Key opinions
- EC2/SES Blocking: Microsoft may block emails sent from EC2 or SES.
- Aggressive Throttling: Hotmail/Outlook aggressively throttles senders, especially new IPs or sudden volume spikes.
- IP Reputation: Maintaining a good IP reputation is crucial for deliverability to Microsoft domains.
- Neighbor Issues: Spillover from IP neighbors can affect deliverability.
- Complaint Feedback: Getting feedback on spam complaints helps identify sending issues.
Key considerations
- Review Bounce Messages: Analyze bounce messages to understand the reason for the rejection.
- Investigate Sending Practices: Examine customer sending practices for potentially problematic behavior.
- Use Custom rDNS: Implement custom reverse DNS to clarify dedicated IPs.
- Consistent Volume: Maintain a consistent sending volume and gradually warm-up new IPs.
- Monitor SNDS: Use SNDS to track IP reputation and identify issues.
- Enroll in JMRP: Sign up for JMRP to receive feedback on spam complaints.
- Address Complaints: Promptly address any spam complaints to improve your sender reputation.
Expert view
Expert from Spam Resource explains that Hotmail/Outlook is notorious for aggressive throttling, especially for new IPs or sudden volume increases. Consistent volume and gradual warm-up are essential.
2 Mar 2023 - Spam Resource
Expert view
Expert from Email Geeks explains that Microsoft may block email sent from EC2 or SES. It is important to look at bounce messages, investigate customer sending practices, and consider custom reverse DNS. If complaints are low, mail might be going to spam. Custom rDNS can clarify dedicated IPs to Amazon, reducing spillover from neighbors and confirming the source of issues.
28 Aug 2023 - Email Geeks
What the documentation says
4 technical articles
Microsoft email bounces are often caused by incorrect email addresses, recipient server issues, SPF failures, and email spoofing. Addressing this involves reviewing bounce message error codes, monitoring IP health via SNDS, and implementing correct SPF and DMARC records to authorize sending servers and prevent spoofing.
Key findings
- Bounce Message Errors: NDRs (bounce messages) indicate various issues like incorrect addresses or server problems.
- SNDS Monitoring: SNDS provides insights into IP health, spam complaints, and trap hits on Microsoft domains.
- SPF Failures: Incorrect or missing SPF records lead to email rejections.
- Email Spoofing: Lack of DMARC implementation allows email spoofing and phishing.
Key considerations
- Review NDR Codes: Carefully examine the error codes in bounce messages to diagnose the cause.
- Monitor IP Health: Use SNDS to regularly monitor your sending IP's health and status.
- Implement SPF Records: Create and maintain accurate SPF records to authorize sending mail servers.
- Implement DMARC: Implement DMARC to prevent email spoofing and define handling of failed authentication checks.
Technical article
Documentation from RFC explains that SPF records specify which mail servers are authorized to send emails on behalf of your domain. Incorrect or missing SPF records can cause Microsoft and other email providers to reject emails from your domain, leading to bounce messages.
16 Sep 2023 - RFC
Technical article
Documentation from DMARC.org explains that implementing DMARC helps prevent email spoofing and phishing attacks. It allows you to specify how receiving email servers should handle emails that fail SPF or DKIM checks, reducing the likelihood of your emails being marked as spam or rejected.
27 Jul 2021 - DMARC.org
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