 <p>Using the <code>foo[]</code> naming hack in PHP causes <code>foo</code> to be an array in $_POST. Since you're just directly copying that array to a variable:</p> <pre><code>$foo = $_POST['foo']; </code></pre> <p>and then embedding that var in your email, you'll just get</p> <pre><code>Se entero: Array </code></pre> <p>in your email. You'll have to do something like:</p> <pre><code>$foo = implode(',', $_POST['foo']); </code></pre> <p>to convert the array into a plain string.</p>