I’ve noticed WordPress’s blog by email feature has the possibility of allowing anyone to see other email addresses. This feature can be turned on in the Admin in Settings->Writings and then Post via e-mail. Let’s say you set that email address as email@example.com, that address will stay hidden. However anyone that emails that address will can have their address exposed on your blog by going to http://example.com/wp-mail.php (assuming that’s where you have WordPress installed at http://example.com). Chances are most people will have this set to a cron job and have it check it every so often, but it might be possible for others to request the page beforehand. And when you do go to that page, it shows something like this:
Author is firstname.lastname@example.org
Posted title: Some Blog Post Title
Mission complete. Message 1 deleted.
Thus, if you are using your a email address you’d like to keep private and you are emailing email@example.com, that email address has the possibility of showing up to people. Which is not good if you email from the same email address that checks the posts. And even worse if you email from a email address for a user in WordPress and has the rights to post contents because the email will get “publish” status rather than “pending” and will go live on the site. And if someone has the email address that is a user and has posting rights, they can easily send fake emails from that address, because all WordPress checks is the From or Reply-To line (whichever it finds first).
It’s easy to prevent it from showing email addresses by opening up wp-mail.php and looking for this line of code
echo '<p>' . sprintf(__('Author is %s'), $author) . '</p>';
And this line of code
echo "\n<p>" . sprintf(__('<strong>Author:</strong> %s'), esc_html($post_author)) . '</p>';
And then you could comment those lines out by putting // in front of both of them.
I understand WordPress outputs this information so you can see logged from any cron jobs you have setup or if you visit the page manually, as a way of just knowing whats going on. However, it could be done better to prevent the addresses from being shown to everyone. A simple solution is to setup a query string and have a secretkey (don’t make this your blog’s password however). For example, lets say your blog is installed at http://example.com/, we are going to know require the following URL to check Posts via e-mail http://example.com/wp-mail.php?secretkey=abc123. And if someone doesn’t send the right secretkey, it won’t check the email address or echo anything out.
So before this line of code
/** Make sure that the WordPress bootstrap has run before continuing. */
if ($_GET['secretkey'] != 'abc123')
Feel free to change the secretkey to whatever you wish. You can also change it to be called something other than secretkey. If you have a cron job, you’ll have to point to that new URL as well http://example.com/wp-mail.php?secretkey=abc123. If you use the secretkey method you can leave the lines where it echoes out the email address if you like (the 2 lines I showed you could comment out).