More information on SPF syntax can be found at The SPF Project. Once you have full access to the Exchange admin center, you should verify that all of your domain names are listed and declared as ...

Microsoft will soon start rolling out Conditional Access policies ... all user access to admin portals such as https://portal.azure.com, Microsoft 365 admin center, and Exchange admin center ...

A New Admin Center Exchange 2007 introduced ... based and fully functional (unlike the ECP in Exchange Server 2010), so you can use URLs to access it both internally and externally -- as long ...