[j-nsp] Looking for paid config - source/port NAT?

[Markus]

Hi list,

I'm looking for someone to create the following config on an M7i with 
12.3R2.5 for me:

Several source addresses on the LAN should not be able to contact port 
25 on the internet, but instead all these connections should be relayed 
through an external mail relay.

I can't seem to figure it out by myself. Not sure if I even need NAT or not.

Anyone available to do this paid & rather quickly? Please contact me 
off-list.

Thank you!
Markus