Email Error: "Not Recognized as a Valid Sender"

This article applies to: Email for Faculty and Staff

This error message indicates that Microsoft has flagged your account as exhibiting spam-like behavior. See our Microsoft's Exchange Online Protection article for details and what to do about it.

Email for Faculty and Staff Articles

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Troubleshooting

Email Error: "Meeting Out of Date"

Office 365 users report seeing repeated notices of "Your meeting was found to be out of date and has been automatically updated." This message appears to be the result of a...

Email Error: "Not Recognized as a Valid Sender"

This error message indicates that Microsoft has flagged your account as exhibiting spam-like behavior. See our Microsoft's Exchange Online Protection article for details and what to do about it...

Email Known Issue: Offline Address Book

In some circumstances (still being investigated), Offline Address Books are not being updated properly for Outlook for Windows and Mac. In addition to affecting searches for contacts, this...

Email Known Issue: Persistent Forwarding Alert

When an email user has set up forwarding from an Office 365 account to an external address (typically set through Outlook on the web), Outlook on the web displays an alert every time the user...

Fraud Detection Warnings on Email Messages

Overview You may have seen warnings on certain email messages, stating that the message's validity could not be verified. The examples shown above are two such ...

Official Mailings via Third-Party Senders

Some Cornell offices, departments, and organizations use third-party senders (for example, Constant Contact, MailChimp, SalesForce, etc.) to distribute official mailings. Sometimes these mailings...

Problem: Email from a Cornell Address Rejected or Refused

Sometimes we get reports that email sent from @cornell.edu addresses to external addresses (or forwarded from a Cornell address to an external address) is being rejected or having delivery refused...

Problem: G Suite Calendar Events that Pass Through Office 365

Microsoft is investigating an issue where calendar events that begin in Google’s G Suite Calendar, go to Office 365, and return to G Suite may not display properly in Google Calendar. Office 365...

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Email Error: "Not Recognized as a Valid Sender"

Email for Faculty and Staff Articles

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