error message between PC card and its own base station: Relaying prohibited

Anyone know what I am doing wrong? I have a Buffalo G54 base station and
have it hard wired into my notebook most of the time.

Yesterday I took the notebook off its docking station and used the Buffalo
802.11g PC card which came with the G54.

It connected to the internet fine but when I tried to send any e-mail (on
any mail box through a number of servers) connecting to this base station it
gave me an error 550 relaying prohibited message and wouldnt send any
e-mail??

I thought I knew what relaying was (I have had the unfortunate experience of
hanging around nanae a bit and seen how some of the loonies there treat what
they call relaying; and I know that this is one of the standard ways AOL
uses at the moment for preventing its members from receiveing e-mail from
non-aol users unless their ISP has paid AOL to deliver their users e-mail)
but I was baffled by such an error message coming from the part of my
connection between my notebook and my own base station

MFS