Bigpond/Optus wireless and Blue Nets outgoing mail server port restrictions

Standard

When out and about and are unable to send mail for no apparent reason or when using a bigpond connection:

Try changing the outgoing mail server port from 25 to either 587 or 9393.

This little workaround should allow you to send mail.
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport $srcPortNumber -j REDIRECT --to-port $dstPortNumber