I am able to add external users to an Office 365 although i have "Allow Outside senders" = Off

[john john]

I have created MS Teams which have created an Office 365 for us. now the Office 365 has the following settings:-

now i thought that since i defined the "Allow Outside senders" to "Off" , then i will not be able to add external users to the Office 365, but this is not the case... as in the above Office 365 i was able to add an external user .. so can anyone advice on this?

[#2]

That setting is for the group mailbox receiving mail from outside the company.

Please see this article for stopping guests from all teams or individual teams.
https://docs.microsoft.com/en-us/microsoftteams/guest-access-powershell