Multiple recieving users for a different documents

Dear Experts,

I am new to Work Flow, and I have the following requirement, please help me out..

I have a parking document in FI, after creation of the document by a user ABC, it should trigger a mail to XYZ, and if a document is created by another user 123 it should trigger a mail to 456.

I have created a simple work flow to trigger a mail into SAP inbox with method Change. But it is triggering the mail to XYZ and 456 at a time created by the both the users.

How can I seperate the mail flow to the different user if the document is created different other users?

Also is it possible to trigger a popup box of the mail to the user? If yes how can we do it?

Please help me out in this regard.

Thanks and Regards,

Praveen.