I have set up port redirection on the ASA 5505 in the following way
static (inside,outside) tcp [global_ip] 80 [inside_ip] 80 netmask 255.255.255.255
static (inside,outside) tcp [global_ip] 25 [inside_ip] 25 netmask 255.255.255.255
static (inside,outside) tcp [global_ip] 443 [inside_ip] 443 netmask 255.255.255.255
and I have set up the appropriate ACL. But I see no traffic and this doesnt work.. it works fine if I use NAT rather than PAT.. also works fine on a ASA 5510