Strange E-Mail string

I noticed that someone else had control over my account, so I went to change my Minecraft account password. Strange enough, I could not login with my E-Mail, because account.mojang.com told me my E-Mail could not be found. I followed the steps on forgot password and after that I could login again. Despite of the main problem solved, I found a bug. The reason because I could not login using my E-Mail is because the E-Mail is replaced with something weird in the launcher and on the website. This is not my Minecraft Account UUID, since that is 2b85d1c760034377b84a8f381d04473b. I don't know what this is and it doesn't look good. Could anyone explain to me what this is?