Actually ...

) it works. As default rule I had Ask for all other requests (except what I normally defined - server's IP, allowed destination ports, allowed source IP (my IP)). I modified only the last rule in Block and Log, I left all other conditions intact, and ...

) it works, and there is nothing blocked in the firewall's events, all logs are access to server's IP on 143 allowed. All I see is green

)
And I don't understand why except for, maybe, a slight problem in the application itself, and this being that it asks for Every Requests, not only for All Other Requests. Is there any other possible explanation?
With this problem solved, I am now truly satisfied with the firewall module, and I cannot wait to have enough patience for the defense+

)