title: Office 365 Advanced Threat Protection is flagging my Firebase Authentication emails
body: <p>I have just today realised that the authorisation emails sent from my perfectly legitimate Firebase backend are being flagged as malicious by Microsoft Outlook's "Advanced Threat Protection"</p>
  
  <p><a href="https://i.stack.imgur.com/mXDsD.png" rel="noreferrer"><img src="https://i.stack.imgur.com/mXDsD.png" alt="enter image description here"></a></p>
  
  <p>There is no reason for this other than perhaps it was flagged during development due to me sending myself repeated confirmation emails in order to test the functionality.</p>
  
  <p>This warning does not show up in regular hotmail/outlook accounts, but I am an Office 365 subscriber so it appears as though I am lucky enough to get this "advanced" protection which protects me from my own completely non-malicious website.</p>
  
  <p>Should I contact Microsoft or Firebase for a solution?</p>
  
  <p>Thanks a lot!</p>
  
  <p>Update: I contacted Firebase support and received the following:</p>
  
  <blockquote>
    <p>My name is XXXX from Firebase Support, thank you for reaching out to us, problems on Microsoft services such as this “Advanced Threat Protection” is not in my area or expertise, I would suggest to open a ticket with Microsoft for this issue, I see that there is already a topic on Stack Overflow, please be sure to check other  Firebase community channels as well.</p>
  </blockquote>
  
  <p>I understand that this isn't Google's problem to solve, but it would seem any Firebase app using email verification is going to run into trouble with Microsoft email systems. Which is a lot of corporate and government systems...</p>
  
  <p>Any suggestions on how to get some attention paid to this from either Google or Microsoft? </p>