Make CI_Email::set_alt_message() parameter mandatory (optional doesn't make sense)
diff --git a/system/libraries/Email.php b/system/libraries/Email.php
index f4efff8..88925e0 100644
--- a/system/libraries/Email.php
+++ b/system/libraries/Email.php
@@ -822,7 +822,7 @@
 	 * @param	string
 	 * @return	CI_Email
 	 */
-	public function set_alt_message($str = '')
+	public function set_alt_message($str)
 	{
 		$this->alt_message = (string) $str;
 		return $this;
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 0344b78..a6fabe1 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -331,7 +331,7 @@
       -  Added option to store raw values instead of CI-formatted ones (APC, Memcache).
       -  Added atomic increment/decrement feature via ``increment()``, ``decrement()``.
 
-   -  :doc:`Email Library <libraries/email>` changes include:
+   -  :doc:`E-mail Library <libraries/email>` changes include:
 
       -  Added a custom filename parameter to ``attach()`` as ``$this->email->attach($filename, $disposition, $newname)``.
       -  Added possibility to send attachment as buffer string in ``attach()`` as ``$this->email->attach($buffer, $disposition, $newname, $mime)``.
diff --git a/user_guide_src/source/libraries/email.rst b/user_guide_src/source/libraries/email.rst
index 3f990b6..ebfde80 100644
--- a/user_guide_src/source/libraries/email.rst
+++ b/user_guide_src/source/libraries/email.rst
@@ -238,7 +238,7 @@
 
 			$this->email->message('This is my message');
 
-	.. method:: set_alt_message([$str = ''])
+	.. method:: set_alt_message($str)
 
 		:param	string	$str: Alternative e-mail message body
 		:returns:	CI_Email instance (method chaining)