Since this is my first post, let me start out by giving a big kudos to the developers for both Wildfire and Spark.
For reference sake, I’'m currently testing Wildfire 2.5.1 (latest at this point) and Spark 1.1.3 (latest as well.)
Suggestion to devs:
When File Transfer option is disabled on the server, the connecting client (Spark in this case) should recognize it and disable the “Send File” button altogether, regardless of client settings.
Add a check box (on by default) in the client config menu called “Activate Send File feature”. Followed by a message in italics stating “When connecting to a Wildfire server, this feature may be disabled in accordance to the active policy.”