You certainly have the right hook, but keep in mind that you are hooking your functionality specifically to the draft_to_publish action, i.e. to the specific case of a post-object pre-existing in the database with draft status being updated to publish. Note that this action ignores drafts which are automatically saved by WordPress when a new post is created – these “drafts” have a post_status of auto-draft.
I’m not exactly sure how you’ve been debugging the issue up to this point, but if you haven’t already, I would recommend verifying that the action itself is firing when you expect it to, perhaps by attaching some simple, arbitrary, and obvious function to it:
function kill_wp( $post ) {
die( 'draft_to_publish fired for post #' . $post['ID'] . ' entitled, "' . $post['post_title'] . '"' );
}
add_action( 'draft_to_publish', 'kill_wp' );
That said, part of your problem may lie in capitalization – the action callback in your example references the function myFunction while the function that is defined has been named myfunction.
Though I am not sure as to what you are trying to accomplish, you could alternately attempt to attach your functionality to the generic action transition_post_status which gets passed the the new status of the post, the previous status of the post, and the post object such that you would have something similar to
function wpse77561_mail_on_publish( $new_status, $old_status, $post ) {
if (get_post_type($post) !== 'post')
return; //Don't touch anything that's not a post (i.e. ignore links and attachments and whatnot )
//If some variety of a draft is being published, dispatch an email
if( ( 'draft' === $old_status || 'auto-draft' === $old_status ) && $new_status === 'publish' ) {
$to = '[email protected]';
$subject="Hi!";
$body = 'Hi,' . chr(10) . chr(10) . 'How are you?';
if( wp_mail( $to, $subject, $body ) ) {
echo('<p>Message successfully sent!</p>');
} else {
echo('<p>Message delivery failed...</p>');
}
}
}
add_action('transition_post_status', 'wpse77561_mail_on_publish');
There are also a number of tools available that might grant you more insight into WordPress’ action execution such as the action hooks inspector for the Debug Bar plugin.