What does this PBEM email mean, please?

[Redpossum]

I am very new to PBEM play. I just completed my first round in the two currently running FOG tourneys, and it was my first experience. I was most impressed with how smooth and easy it all is.

But when I went to the Tourney area of this website and logged in to check my standings, I saw a yellow envelope icon at the top right. I clicked on this and went to my messages. I have a message from the 26th that says, "Hi Redpossum, you have 1 challenge(s) in the Field of Glory II"

OK, but what am I supposed to do? It doesn't say anything about how to respond or...what?

So, I start up the game, click Multiplayer at the main menu and login, go to the "Accept Challenge" tab, and it tells me there are no challenges to accept.

Granted, it's been 5 days. But the same thing happened in FOG Medieval on the 21st and I saw/checked that one the very next day, also finding nothing. What am I doing wrong?