To protect our users from spam, mail sent from your IP address has been temporarily rate limited.ĥ50 5.7.350 Remote server returned message detected as spam -> 550 5.7.1 Įmail authentication verifies that email messages from a sender (for example, are legitimate and come from expected sources for that email domain. Ĥ21-4.7.28 Our system has detected an unusual rate of unsolicited mail originating from your IP address. For this message, DKIM checks did not pass and SPF check for did not pass with ip. The sender must authenticate with at least one of SPF or DKIM.

These issues usually manifest in the form of Non-Delivery Reports (NDR) such as:ĥ50-5.7.26 This mail is unauthenticated, which poses a security risk to the sender and Gmail users and has been blocked. They are configured to reject messages that don't meet email authentication standards. For example, Google has implemented stricter security requirements to authenticate incoming email messages, particularly those sent in large volumes, as announced on the Google blog, Gmail introduces new requirements to fight spam. Microsoft 365 email senders may meet new difficulties in delivering emails to popular email service providers. This is especially important when sending bulk email (large volume email), as it helps maintain the deliverability and reputation of your email campaigns. Please note that using Microsoft 365 to send bulk (mass) email is not a supported use of the service (more details below). By setting up email authentication for your domain, you can ensure that your messages are less likely to be rejected or marked as spam by email providers like Gmail, Yahoo, AOL,. It helps protect recipients from malicious messages, such as spoofing and phishing.

Email authentication is crucial for sending email.

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