Bisa internet, tidak bisa email ym,dll

Mohon pencerahan dari rekan2 ..

Saya baru menginstall ulang Ubuntu server 9.10
saya install, squid, dnsmasq, webmin, iptables.
Kemudian saya melakukan port forwarding agar semua user bisa mengakses internet hanya dengan setting gateway masing2..

iptables.up.rules sebagai berikut :
# Generated by iptables-save v1.4.4 on Thu Feb  4 14:19:59 2010
*nat
:PREROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
# Forward HTTP connections to Squid proxy
-A PREROUTING -p tcp -m tcp -i eth1 --dport 80 -j REDIRECT --to-ports 3128
-A POSTROUTING -j MASQUERADE
COMMIT
# Completed on Thu Feb  4 14:19:59 2010
# Generated by iptables-save v1.4.4 on Thu Feb  4 14:19:59 2010
*mangle
:FORWARD ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]

COMMIT
# Completed on Thu Feb  4 14:19:59 2010
# Generated by iptables-save v1.4.4 on Thu Feb  4 14:19:59 2010
*filter
:FORWARD ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
COMMIT
# Completed on Thu Feb  4 14:19:59 2010

dan akhirnya port forwarding berhasil..koneksi internet lancar dari user..
Namun ternyata hanya browsing saja..saat melakukan koneksi ftp, yahoomessenger, menarik email dari outlook semua gagal.

Padahal sebelumnya berhasil dan semu konfigurasi sama dengan yg sebelumnya..

Mohon bantuannya..
thq