I still have no clarity about what system you were trying to connect to 0.200 with and getting failures. Your answers to #3 were unhelpful:
For 3a you stated that you did not have trouble connecting to the file server (0.200) from the mail server (0.4).
For 3b you stated that you did not have trouble connecting to the file server (0.200) from your router/firewall (address unknown). You also stated that when PF was disabled, you didn't have trouble from the mail server. But you'd already denied having communication trouble in 3a.
For 3c you stated that the device you had trouble connecting to the file server (0.200) was the file server(0.200).
So, giving up, forever, and making the assumption that your mail server and its individual PF configuration is the source of your problem, log onto it and use:
# tcpdump -neti pflog0 action block
That will show you, in real time, what type of IP traffic is being blocked, if you manage to retain the "log" options in your two block rules. What's critical for repairing the problem is for you to understanding what traffic is being blocked, why that traffic is necessary, then writing appropriate pass rules.
I won't try to help you any further.