From their faq page: >> Email can easily be spoofed, but Posterous has come up with some ways to figure out if the email we receive comes from you. If we think

From their faq page: >> Email can easily be spoofed, but Posterous has come up with some ways to figure out if the email we receive comes from you. If we think it might not be you, we ask you to confirm the email before we post it. No matter what, you always get an email notification of every post we put online for your blog, with an easy link to remove the post if you didn't do it.