IIS SMTP relay server hardware sizing

Hi all,

i got a new requirement from management to do sizing for IIS7/SMTP relay server in windows server 2008 r2.

have the following detail

(1) we will use IIS 7/SMTP relay in windows server 2008 r2 to send more then 3 milloin  emails.

(2) each email of size upto 6 MB.

(3) using an application for this  which will send a bunch of more 1 lack emails through IIS/SMTP relay.

i have to recomend hardware/server ( CPU, Memory, NIC, storage etc)