If you start a third-party application which accesses Outlook in a windowless mode (for example „Evatic ERP“) and start Outlook afterwards, this error message appears:
The logon did not suceed, either because one or more of the parameters to MAPILoginEx were invalid or because there were too many sessions open

When you start Outlook first and then the software “Evatic ERP“ there will be no error message.
A Workaround is to start Outlook before you start any application, that accesses Outlook or MAPI Profiles.