Quick and dirty patch to restrict e-mail domains for registration in mahara.

mahara-restrict-email-domains.patch

diff --git a/lang/de.utf8/pieforms.php b/lang/de.utf8/pieforms.php
index 4d6ced8..03d0fee 100644
--- a/lang/de.utf8/pieforms.php
+++ b/lang/de.utf8/pieforms.php
@@ -18,7 +18,7 @@ $string['element.expiry.noenddate'] = 'Kein Enddatum';
 $string['element.expiry.weeks'] = 'Wochen';
 $string['element.expiry.years'] = 'Jahre';
 $string['rule.before.before'] = 'Dies kann nicht nach dem Feld "%s" sein';
-$string['rule.email.email'] = 'Die E-Mail Adresse ist ungültig';
+$string['rule.email.email'] = 'Die E-Mail Adresse ist ungültig. Bitte beachten Sie das nur E-Mailaddressen von den Domains foo.com und baz.de zugelassen sind.';
 $string['rule.integer.integer'] = 'Das Feld muss eine ganze Zahl (integer) sein';
 $string['rule.maxlength.maxlength'] = 'Das Feld darf höchstens %d Zeichen lang sein';
 $string['rule.maxvalue.maxvalue'] = 'Dieser Wert kann nicht größer als %d sein';
diff --git a/lang/en.utf8/pieforms.php b/lang/en.utf8/pieforms.php
index 972b5c3..10b93e9 100644
--- a/lang/en.utf8/pieforms.php
+++ b/lang/en.utf8/pieforms.php
@@ -37,7 +37,7 @@ $string['element.color.transparent'] = 'Use theme colour';
 
 $string['rule.before.before'] = 'This cannot be after the field "%s"';
 
-$string['rule.email.email'] = 'Email address is invalid';
+$string['rule.email.email'] = 'Email address is invalid. Please consider that only addresses from the domains foo.com and baz.de are valid.';
 
 $string['rule.integer.integer'] = 'The field must be an integer';
 
diff --git a/lib/pieforms/pieform/rules/email.php b/lib/pieforms/pieform/rules/email.php
index ea2afa8..60c43a6 100644
--- a/lib/pieforms/pieform/rules/email.php
+++ b/lib/pieforms/pieform/rules/email.php
@@ -37,7 +37,7 @@
  *                         the address.
  */
 function pieform_rule_email(Pieform $form, $value, $element) {/*{{{*/
-    if (!preg_match('/^[A-Za-z0-9+\._%-]+@(?:[A-Za-z0-9-]+\.)+[a-z]{2,4}$/', $value)) {
+    if (!preg_match('/^[A-Za-z0-9+\._%-]+@(.*\.)?(foo\.com|baz\.de)$/', $value)) {
         return $form->i18n('rule', 'email', 'email', $element);
     }
 }/*}}}*/