...status" from tools online and it does not report to be an open relay.
In the exchange log I enabled I get many entries such as this:
0,,1.2.3.4,*,,attempting to connect
1,192.168.1.100:3572,1.2.3.4,+,,
2,192.168.1.100:3572,1.2.3.4,<,220 PcComputerGuy.com ESMTP Postfix (Debian/GNU)...