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arnotixe's avatar
arnotixe
Copper Contributor
Feb 22, 2023

Firebase authentication emails are blocked by Office 365

Many of my customers are recently not getting any authentication emails from my apps anymore. The DKIM keys are setup, authorized senders and so on.   The authentication emails do go through to non...
microsoft 365 defender
office 365
FcoManigrasso's avatar
FcoManigrasso
Iron Contributor
Feb 27, 2023

Hi arnotixe,

 

Thanks for sending me a test message.

It was Quarantined by O365 as High Spam/Phish.

The problems that I see here are 2 main ones. On one hand the links are considered dangerous, ( but that probably can be easily solved fixing the other problem.

On the other hand, your sending server is blacklisted: mail-vs1-f70.google.com (209.85.217.70)

So, basically you need to ensure to delist it or use another relay for such deliveries. DKIM passes, but the sender server has low reputation. 

arnotixe's avatar
arnotixe
Copper Contributor
Feb 27, 2023
Wondering who to contact next, as the server itself is probably sending out on behalf of many different identities.
This problem is currently affecting 74 of my business customers.

The way it looks now, setting up a different outbound server for these mails (serving only my domain for example) would be the only option?
  • FcoManigrasso's avatar
    FcoManigrasso
    Iron Contributor
    Feb 27, 2023

    Hi arnotixe,

    Not sure if I got your question. But you have many options...

    - Ask the provider to delist.

    - Use another relay

    - Request the recipients IT teams to whitelist you, ( probably rejected by the Security teams. Think that they have no control over the sender servers... You neither. Too risky ).

    And probably other options depending on your environment and requirements. 

    The point is basically that O365 identifies your messages as SPAM/Phish and is quarantining all your messages.

    • arnotixe's avatar
      arnotixe
      Copper Contributor
      Mar 14, 2023
      yeah this is still a problem (exclusively for Microsoft customers) even after having purchased a Dedicated IP to send with…
      • FcoManigrasso's avatar
        FcoManigrasso
        Iron Contributor
        Mar 15, 2023

        Hi arnotixe,

         

        I just analyzed the new test message that you sent me and it passes the security scans and it's not identified as Bulk. The only problem is the SCL level, (5), and by default EOP will deliver those messages to the Junk email folder. ( Note that this can be modified by the Admins, so it's possible that in some cases it landes in the inbox folder and in other ones it will be quarantined ).

        I'll share the message header with you in a private message. Finde here more information about the SCL value:

         

        https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/anti-spam-spam-confidence-level-scl-about?view=o365-worldwide

        https://learn.microsoft.com/en-us/exchange/antispam-and-antimalware/antispam-protection/antispam-stamps?view=exchserver-2019

        https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/message-headers-eop-mdo?view=o365-worldwide

         

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