Microsoft Error 2400 inside Outlook on my New Android when I try to connect my Microsoft 365 email account

Paul Pursell 0 Reputation points

I am having an error message 2400 on my New Android phone that I am trying to connect a Microsoft 365 email to through Outlook. I have this email on my personal desktop and another phone through Outlook but it will not connect on the new android phone. How do I get the email connected up? Again it give me an Error Message 2400 when I try to add my Office 365 email. Thanks.

Outlook Management
Outlook Management
Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Q&A Assist
    AI generated content. This question contains an answer created with AI from Q&A Assist. Learn more

    Based on the error message you are receiving, it seems that you are unable to connect your Microsoft 365 email account to Outlook on your new Android phone. Error 2400 is a generic error message that can occur due to various reasons. One possible cause could be that the version of Exchange Server that you're running uses TLS 1.1 or 1.0, which are deprecated and no longer supported by Outlook for iOS and Outlook for Android. Another possible cause could be that the user has an account at a third-party provider that uses the same email address and password that the user's Microsoft 365 account uses.

    To resolve this issue, you can try the following steps:

    1. Confirm that ActiveSync is enabled for the user in the Exchange admin center.
    2. Confirm that the mobile device isn't blocked by an ActiveSync quarantine rule in the Exchange admin center.
    3. Create a new alias for the user in Microsoft 365 and use it to set up Outlook.
    4. Change the user name or password of the user's Microsoft 365 account or of the user's third-party account so that it is unique for the user's Microsoft 365 account.

    If none of these steps resolve the issue, you may want to check if your Exchange account is already added to Outlook on another device, as mailbox synchronization might stop unexpectedly in such cases.


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  2. SokiGuo-MSFT 18,901 Reputation points Microsoft Vendor

    Hi @Paul Pursell

    Looks like the issue is more related to Outlook for mobile. Please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. In order to better solve your problem, it's suggested to post your issue on this dedicated forum for Outlook for Mobile for more professional help.

    There is a similar thread here, please try the solutions mentioned inside to check if that helps.

    Hope this helps!

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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