Some details on what mail you're checking? I've not had that problem, and I've not seen others here complaining about it, so I see two possibilities:
-If your ISP is providing the e-mail you're checking they may be restricting access to their servers to users that are connected to their network.
-The hotspots you're using may be restricting traffic to port 80 so html pages may be the only thing coming through.
Those are just off the top of my head, I'm sure there are other possibilities. More detail should help us sort out your problem.