If your blog is on your main site, you use http://www.mysite.com/wp-mail.php
If your blog is in a sub folder, you use http://www.mysite.com/blog/wp-mail.php
* replace 'blog' with whatever the folder's name is.
Also, make sure you are sending the e-mail from an account in your users with editor permissions. Example:
Go to Users > Add new...
Call the user Me at work, or Me going mobile, etc...
Add your Name to the First and Last blocks
This is the important part!!!!! type in the e-mail address you want to send from!
Make this user an editor or admin
Now, send an email from the e-mail account of the user you just added to your secret e-mail address you set up on the writing page (Settings...writing).
Run the wp-mail.php script by typing the script path into your browser.
If your post came out funky looking, be sure to send only plain text.
If your post came over in a pending status, you sent it from an e-mail account that is not an editor or admin on your blog.
I'd recommend setting the wp-mail.php script in the footer of your theme as explained in the Codex help page for sending via e-mail. Put the iframe in just before </body>.