diff --git a/includes/common.inc b/includes/common.inc
index 39836589f59aac63dfd342fce5b13f247e7f2d18..0ebe85707146075e580e5aeef0d6a8746b83c6a4 100644
--- a/includes/common.inc
+++ b/includes/common.inc
@@ -1167,7 +1167,8 @@ function fix_gpc_magic() {
 /**
  * Verifies the syntax of the given e-mail address.
  *
- * See @link http://tools.ietf.org/html/rfc5321 RFC 5321 @endlink for details.
+ * This uses the
+ * @link http://php.net/manual/filter.filters.validate.php PHP e-mail validation filter. @endlink
  *
  * @param $mail
  *   A string containing an e-mail address.
diff --git a/includes/mail.inc b/includes/mail.inc
index 630494ae52648416e65ee711136b98c167757908..bbb55357d4b896d946e6488665bc1b32e536e908 100644
--- a/includes/mail.inc
+++ b/includes/mail.inc
@@ -93,7 +93,9 @@
  *   will be {$module}_{$key}.
  * @param $to
  *   The e-mail address or addresses where the message will be sent to. The
- *   formatting of this string must comply with RFC 2822. Some examples are:
+ *   formatting of this string will be validated with the
+ *   @link http://php.net/manual/filter.filters.validate.php PHP e-mail validation filter. @endlink
+ *   Some examples are:
  *   - user@example.com
  *   - user@example.com, anotheruser@example.com
  *   - User <user@example.com>
@@ -307,19 +309,21 @@ public function format(array $message);
    *   - id: A unique identifier of the e-mail type. Examples: 'contact_user_copy',
    *     'user_password_reset'.
    *   - to: The mail address or addresses where the message will be sent to.
-   *     The formatting of this string must comply with RFC 2822. Some examples:
+   *     The formatting of this string will be validated with the
+   *     @link http://php.net/manual/filter.filters.validate.php PHP e-mail validation filter. @endlink
+   *     Some examples are:
    *     - user@example.com
    *     - user@example.com, anotheruser@example.com
    *     - User <user@example.com>
    *     - User <user@example.com>, Another User <anotheruser@example.com>
-   *    - subject: Subject of the e-mail to be sent. This must not contain any
-   *      newline characters, or the mail may not be sent properly.
-   *    - body: Message to be sent. Accepts both CRLF and LF line-endings.
-   *      E-mail bodies must be wrapped. You can use drupal_wrap_mail() for
-   *      smart plain text wrapping.
-   *    - headers: Associative array containing all additional mail headers not
-   *      defined by one of the other parameters.  PHP's mail() looks for Cc
-   *      and Bcc headers and sends the mail to addresses in these headers too.
+   *   - subject: Subject of the e-mail to be sent. This must not contain any
+   *     newline characters, or the mail may not be sent properly.
+   *   - body: Message to be sent. Accepts both CRLF and LF line-endings.
+   *     E-mail bodies must be wrapped. You can use drupal_wrap_mail() for
+   *     smart plain text wrapping.
+   *   - headers: Associative array containing all additional mail headers not
+   *     defined by one of the other parameters.  PHP's mail() looks for Cc and
+   *     Bcc headers and sends the mail to addresses in these headers too.
    *
    * @return
    *   TRUE if the mail was successfully accepted for delivery, otherwise FALSE.
diff --git a/modules/system/system.api.php b/modules/system/system.api.php
index db1a9114617190279d2bd8e4fb4eedf65c9ed2b4..777af8cd3018f55bc02f322e17152d9f7663391e 100644
--- a/modules/system/system.api.php
+++ b/modules/system/system.api.php
@@ -1929,8 +1929,9 @@ function hook_image_toolkits() {
  *     The drupal_mail() id of the message. Look at module source code or
  *     drupal_mail() for possible id values.
  *  - 'to':
- *     The address or addresses the message will be sent to. The
- *     formatting of this string must comply with RFC 2822.
+ *     The address or addresses the message will be sent to. The formatting of
+ *     this string will be validated with the
+ *     @link http://php.net/manual/filter.filters.validate.php PHP e-mail validation filter. @endlink
  *  - 'from':
  *     The address the message will be marked as being from, which is
  *     either a custom address or the site-wide default email address.
@@ -2478,8 +2479,9 @@ function hook_watchdog(array $log_entry) {
  *   An array to be filled in. Elements in this array include:
  *   - id: An ID to identify the mail sent. Look at module source code
  *     or drupal_mail() for possible id values.
- *   - to: The address or addresses the message will be sent to. The
- *     formatting of this string must comply with RFC 2822.
+ *   - to: The address or addresses the message will be sent to. The formatting
+ *     of this string will be validated with the
+ *     @link http://php.net/manual/filter.filters.validate.php PHP e-mail validation filter. @endlink
  *   - subject: Subject of the e-mail to be sent. This must not contain any
  *     newline characters, or the mail may not be sent properly. drupal_mail()
  *     sets this to an empty string when the hook is invoked.