+/**
+ * E-mail address validation
+ */
+function check_email($email)
+{
+ // Check for invalid characters
+ if (preg_match('/[\x00-\x1F\x7F-\xFF]/', $email))
+ return false;
+
+ // Check that there's one @ symbol, and that the lengths are right
+ if (!preg_match('/^([^@]{1,64})@([^@]{1,255})$/', $email, $email_array))
+ return false;
+
+ // Check local part
+ $local_array = explode('.', $email_array[1]);
+ foreach ($local_array as $local_part)
+ if (!preg_match('/^(([A-Za-z0-9!#$%&\'*+\/=?^_`{|}~-]+)|("[^"]+"))$/', $local_part))
+ return false;
+
+ // Check domain part
+ if (preg_match('/^(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])(\.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])){3}$/', $email_array[2])
+ || preg_match('/^\[(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])(\.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9]?[0-9])){3}\]$/', $email_array[2]))
+ return true; // If an IP address
+ else {
+ // If not an IP address
+ $domain_array = explode('.', $email_array[2]);
+ if (sizeof($domain_array) < 2)
+ return false; // Not enough parts to be a valid domain
+
+ foreach ($domain_array as $domain_part)
+ if (!preg_match('/^(([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|([A-Za-z0-9]))$/', $domain_part))
+ return false;
+
+ if (!rcmail::get_instance()->config->get('email_dns_check'))
+ return true;
+
+ if (strtoupper(substr(PHP_OS, 0, 3)) == 'WIN' && version_compare(PHP_VERSION, '5.3.0', '<'))
+ return true;
+
+ // find MX record(s)
+ if (getmxrr($email_array[2], $mx_records))
+ return true;
+
+ // find any DNS record
+ if (checkdnsrr($email_array[2], 'ANY'))
+ return true;
+ }
+
+ return false;
+}
+