And where is that account? My guess: on some mail-server. Then WLM is kind enough to warn you that your account on the mail-server is hacked. A good choice to stick to WLM then, if it gives such a warning. Unsure if other mail-programs do that. Worth a try with Thunderbird.
But maybe my guess is totally wrong.
I get this message each and every time I open my WLM. I've googled on how to remove it but haven't had any luck. I want to stick with using WLM