The MIME version can be used in all types of e-mail. Fixes #14.

lib/Cake/Network/CakeEmail.php

@@ -630,8 +630,8 @@ class CakeEmail {
 			$headers['Subject'] = $this->_subject;
 		}
 
+		$headers['MIME-Version'] = '1.0';
 		if (!empty($this->_attachments)) {
-			$headers['MIME-Version'] = '1.0';
 			$headers['Content-Type'] = 'multipart/mixed; boundary="' . $this->_boundary . '"';
 			$headers[] = 'This part of the E-mail should never be seen. If';
 			$headers[] = 'you are reading this, consider upgrading your e-mail';

lib/Cake/tests/Case/Network/CakeEmailTest.php

@@ -392,6 +392,7 @@ class CakeEmailTest extends CakeTestCase {
 			'X-Something' => 'nice',
 			'X-Mailer' => 'CakePHP Email Component',
 			'Date' => date(DATE_RFC2822),
+			'MIME-Version' => '1.0',
 			'Content-Type' => 'text/plain; charset=UTF-8',
 			'Content-Transfer-Encoding' => '7bit'
 		);
@@ -403,6 +404,7 @@ class CakeEmailTest extends CakeTestCase {
 			'X-Other' => 'cool',
 			'X-Mailer' => 'CakePHP Email Component',
 			'Date' => date(DATE_RFC2822),
+			'MIME-Version' => '1.0',
 			'Content-Type' => 'text/plain; charset=UTF-8',
 			'Content-Transfer-Encoding' => '7bit'
 		);
@@ -417,6 +419,7 @@ class CakeEmailTest extends CakeTestCase {
 			'X-Other' => 'cool',
 			'X-Mailer' => 'CakePHP Email Component',
 			'Date' => date(DATE_RFC2822),
+			'MIME-Version' => '1.0',
 			'Content-Type' => 'text/plain; charset=UTF-8',
 			'Content-Transfer-Encoding' => '7bit'
 		);
@@ -434,6 +437,7 @@ class CakeEmailTest extends CakeTestCase {
 			'X-Other' => 'cool',
 			'X-Mailer' => 'CakePHP Email Component',
 			'Date' => date(DATE_RFC2822),
+			'MIME-Version' => '1.0',
 			'Content-Type' => 'text/plain; charset=UTF-8',
 			'Content-Transfer-Encoding' => '7bit'
 		);