diff --git a/htmlmail.admin.inc b/htmlmail.admin.inc
index 40148a3..0ef1a3f 100644
--- a/htmlmail.admin.inc
+++ b/htmlmail.admin.inc
@@ -255,6 +255,15 @@ function htmlmail_test_form($form_values = NULL) {
     '#format' => $defaults['body']['format'],
     '#required' => TRUE,
   );
+  $mailsystem = mailsystem_get();
+  $form['class'] = array(
+    '#type' => 'select',
+    '#title' => t('Test mail sending class'),
+    '#default_value' => $mailsystem['htmlmail'],
+    '#options' => array_combine(mailsystem_get_classes(), mailsystem_get_classes()),
+    '#description' => 'Select the MailSystemInterface implementation to be tested.',
+  );
+
   $form['submit'] = array(
     '#type' => 'submit',
     '#value' => t('Send test message'),
@@ -274,6 +283,8 @@ function htmlmail_test_form_submit($form, &$form_state) {
   );
   // Set the defaults for reuse.
   variable_set('htmlmail_test', $defaults);
+  // Set the mail sending class.
+  mailsystem_set(array('htmlmail' => $form_state['values']['class']));
   // Send the email.
   $params = array(
     'subject' => $form_state['values']['subject'],
diff --git a/htmlmail.install b/htmlmail.install
index 9ae4c83..2834b9b 100644
--- a/htmlmail.install
+++ b/htmlmail.install
@@ -17,10 +17,6 @@ function htmlmail_requirements($phase) {
     return $result;
   }
   if (module_load_include('inc', 'mailsystem', 'html_to_text') !== FALSE) {
-    // Ensure that the HTMLMailSystem class is used by
-    // (at least) the htmlmail module, so that it always
-    // shows up on the admin/config/system/mailsystem page.
-    mailsystem_set(array('htmlmail' => 'HTMLMailSystem'));
     return $result;
   }
   $args = array(
diff --git a/htmlmail.mail.inc b/htmlmail.mail.inc
index 16fe7cd..d882c5c 100644
--- a/htmlmail.mail.inc
+++ b/htmlmail.mail.inc
@@ -46,7 +46,7 @@ class HTMLMailSystem implements MailSystemInterface {
     }
     else {
       if (is_array($message['body'])) {
-        $message['body'] = implode("$eol$eol", $message['body']);
+        $message['body'] = implode("<br />$eol<br />$eol", $message['body']);
       }
       $body = theme('htmlmail', $message);
       if ($message['body'] && !$body) {