New Outlook on Win11 cannot send e-mails

Stephan Lehmann 0 Reputation points
2026-11-10T22:52:48.7466667+00:00

I installed Microsoft 365 on my new computer. Seems that new Outlook was already installed before. I setup my e-mail account (POP/SMTP). New Outlook receives messages. But sending fails. There comes a response "could not send", because of authentication failure. The dialogue in classic Outlook showed the option "use same settings as for receiving", the new Outlook has no such setting. For me it looks like new Outlook uses wrong credentials for sending.
So i installed Outlook classic, and everything works.
(using SMTP port 465 with SSL/TLS)

Microsoft 365 and Office | Other
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  1. Manoel Barros 23,460 Reputation points Independent Advisor
    2026-11-10T23:38:10.2666667+00:00

    Hi!

    First, it is important to know whether you are referring to the "New Outlook" or "Outlook Classic."

    Outlook Classic is generally included with Microsoft 365, which is a subscription-based service. The New Outlook, on the other hand, is free and typically comes pre-installed on new computers. You can usually distinguish between them by their icons:

    CDN media

    The new Outlook does not support POP email accounts—only IMAP—and you cannot fully customize provider settings, as these are configured automatically.

    If you are using the classic version, try adding the account as follows:

    1. Press Windows + R > type control > Under "View by," select Large icons > Click on Mail (Microsoft Outlook).

    ATTENTION: If you use a POP email account, you should back up your data files as a precaution; they can typically be found under Documents > Outlook Files.

    1. Click Show Profiles > Remove your current profile > Close the Mail windows.
    2. Open the Mail settings again > Click Show Profiles > Select Add > Enter a name > Return to the previous window and click Add Account.
    3. Select Manual setup or additional server types > Choose POP or IMAP > Fill in the required fields with your account information.
    4. Click More Settings > Enter the necessary details under the Outgoing Server and Advanced tabs.
    5. Click OK > Next.

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