[nznog] smtp via xtra seems blocked

Hi, This morning a client called up to advise all their PC's stopped being able to send via my smtp server which they had been able to do an hr before. I suggested they reboot their router (M1122) which they did, however smtp still doesn't work. I had the client connect using smtp.xtra and they had no issues, further tests indicated they could ping the smtp, connect to port 80 on it but not port 25, not even mail.orcon.net.nz, this happens on all 14 hosts. The user has no firewall settings on the router, no local firewall and is using nod32. Just wondering if anyone is aware of xtra blocking port 25 ? Cheers Barry