Why are fully authenticated emails marked as 'Unverified Sender' in Outlook/Hotmail?

Email marketer from EmailToolTester shares that to avoid spam filters, including those that might cause an email to be marked as 'Unverified Sender', you should ensure your sender reputation is high. Also you should clean your email list, avoid spam trigger words, ensure your content is relevant, and also you should test your email before sending it to large lists.

Email marketer from Reddit suggests that Outlook often marks emails as 'Unverified Sender' because of issues with the sender's domain reputation or because the email content triggers spam filters, even if authentication (SPF, DKIM, DMARC) is properly configured.

Email marketer from GlockApps recommends thoroughly testing your emails before sending them to your subscribers. Use email testing tools to check your sender score, authentication setup, and placement in various inboxes (including spam folders). Testing helps identify and fix potential deliverability issues before they impact your sending reputation.

Email marketer from Reddit explains that new IPs or domains often face deliverability challenges, including being marked as 'Unverified Sender', until they establish a positive reputation with Microsoft. Warming up the IP and domain gradually by sending low volumes of high-quality emails is crucial.

Email marketer from AuthSMTP shares that sender reputation is a score assigned to sending IP addresses and domains, based on their email sending behavior. Factors that influence sender reputation include email volume, complaint rates, spam trap hits, and authentication practices. Maintaining a positive sender reputation is critical for ensuring high email deliverability and avoiding being marked as 'Unverified Sender'.

Email marketer from StackOverflow explains that DKIM provides a method for verifying the authenticity of an email message through cryptographic signatures. To ensure proper setup, you need to generate a DKIM key pair, publish the public key in your DNS records, and configure your mail server to sign outgoing emails with the private key. Incomplete or improperly configured DKIM can result in authentication failures.

Email marketer from Mailjet shares that the ‘Unverified Sender’ warning in Outlook/Hotmail is an indicator that the email may be suspicious. The warning appears when Outlook cannot verify the identity of the sender, this can happen for various reasons, including issues with email authentication (SPF, DKIM, DMARC) or the sender's reputation. It is always best practice to properly authenticate your emails and maintain a good sender reputation to avoid such warnings.

Email marketer from Email Geeks confirms that authenticated emails are being marked as 'Unverified sender' and going to junk despite passing SPF, DKIM, and DMARC checks. He suspects something is broken at Microsoft.

Email marketer from SendGrid explains that warming up a new IP address is essential for establishing a positive sending reputation with mailbox providers. Start by sending low volumes of email to engaged subscribers, gradually increasing the volume over time. Monitor your delivery rates and engagement metrics closely to adjust your sending schedule as needed.

Expert from Word to the Wise explains that Microsoft may mark authenticated emails as 'Unverified' due to factors beyond authentication, such as content reputation, sending patterns, or user complaints. Microsoft's algorithms consider numerous signals, and even a small number of negative signals can impact deliverability and verification status.

Expert from Word to the Wise explains Microsoft is now using unverified domain icons even when SPF and DKIM is setup correctly. She suggests that your best defence to this is list hygiene to improve sender reputation with real people.

Expert from Email Geeks suggests that the issue with authenticated emails being marked as 'Unverified sender' in Outlook/Hotmail may be due to a recently deployed and potentially broken Microsoft feature. She suggests waiting a week or so for Microsoft to fix it before investing significant time in troubleshooting.

Documentation from Microsoft indicates that emails can be marked as unverified due to missing or invalid SPF, DKIM, or DMARC records. They recommend ensuring that these records are correctly configured and that the sending domain has a good reputation. Transient issues with DNS propagation or temporary glitches on Microsoft's side could also contribute.

Documentation from RFC describes how to properly configure SPF records to ensure that sending mail servers are authorized to send email on behalf of your domain. Having an invalid or incorrect SPF record will almost certainly cause deliverability issues.

Documentation from DMARC.org suggests DMARC builds upon SPF and DKIM to provide instructions to email receivers on how to handle messages that fail authentication checks. Implementing DMARC correctly involves publishing a DMARC policy in your DNS records that specifies how receivers should treat unauthenticated messages (e.g., reject, quarantine, or none). Correct DMARC implementation helps prevent email spoofing and phishing attacks.

Documentation from Google Workspace shares that to improve email deliverability and prevent being marked as 'Unverified Sender', you should ensure your sending domain and IPs are not blacklisted. Monitor your domain and IP reputation using tools like Google Postmaster Tools, and promptly address any issues identified. Maintaining a clean sending infrastructure is essential for positive deliverability.

Documentation from SparkPost highlights the importance of using strong email authentication (SPF, DKIM, and DMARC) to protect your sending domain from spoofing and phishing attacks. Implementing these standards correctly signals to mailbox providers that your emails are legitimate and should be delivered to the inbox.

Documentation from Microsoft explains that the 'Unverified Sender' mark in Outlook is designed to alert users to potentially suspicious messages. The system checks various signals, including authentication records, sender reputation, and content characteristics, to determine whether a sender is verified. Even with proper authentication, other factors can trigger the warning.