I like my Mail-To-Blogger email address! Why does Google tell me to change my "secret word"?
Some owners of private blogs believe that their blog is invisible to hackers and spammers, as an ostrich sticking his head into a hole in the ground becomes invisible to predators. If you combine a private blog with an activated Mail-to-Blogger address, using an easily guessed "secret word", you have yet another future spam host.
Hackers don't care about the name of the blog, or the fact that the blog is private. Their script starts with a working email address, from which they derive the public portion of the Mail-to-Blogger email address. Given an easily guessed "secret word" - the private portion of the Mail-to-Blogger email address - they have yet another blog on which they can publish their ads, or their spam links.
One day, we have yet another plaintive cry in Blogger Help Forum: Something Is Broken about unknown parties publishing to their blog, at will.
Where are these ads coming from? I don't want spam on my blog!
Since some blog owners don't check their blogs daily, it's even possible that the Blogger anti-spam classification process will, righteously, detect the blog as a spam host, and lock or delete it. Then, we see yet another cry of anguish.
My blog isn't spam! It's just my blog!! Why does Blogger persecute me??!!
If you get a notice or warning from Google, requiring that you change your Mail-to-Blogger "secret word", please take it seriously. Google really does have your best interests in mind.