In Microsoft Office 365, when you try to open Microsoft Outlook Web App by using a web browser such as Safari, you receive the following error message:
Cannot use this ID to access this service. Please sign-in with a different ID.
When you use Windows Internet Explorer, Outlook Web App opens successfully.
This issue occurs when you try to open Outlook Web App by using a URL that points to a site that requires Microsoft account (formerly Windows Live ID) credentials. And, this site doesn't accept a user ID. For example, you use the following URL:
To resolve this issue, use a URL that resembles the following to access Outlook Web App in Office 365:
For example if your domain is contoso.onmicrosoft.com, the URL that you'd use is as follows:
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