How do I troubleshoot email delivery issues in Microsoft 365?
Summary
What email marketers say7Marketer opinions
Email marketer from Reddit explains the first step is to check the recipient's junk email folder. Sometimes, legitimate emails are mistakenly flagged as spam.
Email marketer from Reddit shares to check if your sending IP address is blacklisted on any major blocklists. Being blacklisted can severely impact deliverability. Use online tools to check your IP reputation.
Email marketer from Spiceworks Forums explains that sender reputation is crucial. Poor sender reputation can lead to emails being filtered or blocked. Monitor your sender score using services like Sender Score or Talos.
Email marketer from SuperUser details how SPF, DKIM, and DMARC records help verify the authenticity of your emails. Implement these records correctly to improve deliverability and reduce the chances of your emails being marked as spam.
Email marketer from EmailOnAcid Blog shares that setting up feedback loops with major ISPs allows you to receive reports about spam complaints from their users, enabling you to identify and address potential issues with your sending practices.
Marketer from Email Geeks suggests checking the Exchange inbound message audit logs for clues and the defender quarantine logs if emails are disappearing. They also point out a specific error related to mailboxes exceeding 1M items in a folder and advises checking the M365 Service Health dashboard for reported issues.
Email marketer from Microsoft Tech Community recommends reviewing Exchange Online Protection (EOP) settings to ensure that they are not overly restrictive. Check spam filter policies, connection filters, and outbound spam policies.
What the experts say2Expert opinions
Expert from Word to the Wise explains that after migrating to Microsoft 365, deliverability issues can arise from changes in IP addresses and sending infrastructure. It's important to warm up new IP addresses gradually, monitor sender reputation, and ensure proper authentication (SPF, DKIM, DMARC) is in place to establish trust with ISPs.
Expert from SpamResource details that several factors can cause delivery issues. These include poor IP reputation, incorrect authentication records (SPF, DKIM, DMARC), high spam complaint rates, sending to invalid email addresses, and being blacklisted by anti-spam organizations. Monitoring these factors is crucial for maintaining good deliverability.
What the documentation says4Technical articles
Documentation from Microsoft Learn explains that NDRs, also known as bounce messages, provide information about why an email wasn't delivered. You should Examine the enhanced status code and the diagnostic code in the NDR for specific error information to diagnose the problem.
Documentation from Microsoft Learn details the importance of properly configuring DNS records (SPF, DKIM, DMARC) to authenticate email and prevent spoofing. It emphasizes that incorrect DNS settings can lead to delivery failures.
Documentation from Microsoft Learn explains that message trace in the Exchange admin center (EAC) allows you to track email messages as they pass through the Exchange Online service. It can help you identify where a message got delayed, rejected, or delivered.
Documentation from Microsoft Learn shares that the Microsoft Remote Connectivity Analyzer can be used to test inbound and outbound mail flow. It simulates email traffic and identifies potential issues with DNS, connectivity, and certificate validation.