Can anyone post into my blog from any email address?

Here I am trying to send a post to a blogger given email ID from a unrelated email address and if this succeeds to appear as a post on my blog, then I'd be not awed but SHOCKED. Because it's a damn privacy/security concern indeed. Now anyone can come and post anything if they just knew my blogger given email ID (which ofcourse it allowed me to change, but that definitely is not adequate protection by any means).