We (actually our DBA) are setting up a sharepoint server. One of the web parts she is trying to use is trying to send an email but gets the error above.
When i ran a wireshark capture on the sharepoint server, i see that the web part is using auth ntlm. I don't think it should need to since its not sending externally, only internally. Also, I'm not sure who it's authenticating as.
i found online to run this command: Add-AdPermission -Identity "Default Receive Connector" -User "NT AUTHORITY\Authenticated Users" -ExtendedRights ms-Exch-SMTP-Accept-Any-Sender
However, if i do that I'm not sure what consequences it will have. does this open up a security hole?