Hello Elham,
I don't get it "which scenario" . There would be a common URL for every bidder which would be handled by the portal consultant . Once bidder clicks on the URL , he/she has to provide her credentials . After providing the credentials , it will be redirected to the SRM , where he/she can see the Rfx which are ready for the bidding. They will open the particular Rfx and provide their quotation value in the item and then will click on Submit button. As they click on Submit button his final quotation will be automatically be reflected in our(means the actual user) Rfx screen. Once the rfx reached the end date , user can see the quoted value.
For email , when the vendors are created we provide the information like address , name , email . So no need to provide an email for the price , Everything is handled by the SRM system.
Document!! for which configuration ?? SOST are checked whether email is getting triggered or not. If not then you have to maintain the same with the help of Basis team
I hope this helps 
BR
Gaurav Gautam