not able to send and recive mail

hi friend
i have 4 pc .all win98(frist edi.) installed.i am sharing internet through winproxy software.on my client pc i can brows internet but i can not send and recive mail so i cheked in winproxy software there is ok .i got connection failed to connect server in outlook express i cheked everything there is ok .plse tell me why this happen i wating for answer plse