Detect e-Mailaccount for Mails in Queue

[Thomas_Krcal]

Hello I have two questions concerning the same subject.

1> I have some Spam mails in the Mail queue.
Sender and Receiver of this Mails are some strange and unknown E-Mails.
How can I detect from witch real E-Mail account on the Server this mail were sent.

2> Is it possible to allow to send mails only from real and known e-Mails, created on the server.
So that the Sender e-Mail can only be on Account created on the Server.

Thank you.