Front door leaking - letterbox?

ElephantBoy57

Recently I noticed that the carpet in my front porch was soaking wet. I did have a leaking window, which was sorted out about 3 weeks ago. I didn't notice the carpet then. I have dried the 3 layers of carpet, but don't want to put it back down until I know the porch is leak-free.

When the rain was heavy, I noticed rain pouring in from the letterbox, even though it looks perfectly sealed. The bottom of the door frame looked dry, but I am reluctant to blame all the water on the letterbox leaking.