--- old/core/email_api.php	2018-07-16 23:58:00.598800300 +0200
+++ new/core/email_api.php	2018-07-16 23:56:47.670800300 +0200
@@ -530,7 +530,8 @@
 	# Send signup email regardless of mail notification pref
 	# or else users won't be able to sign up
 	if( !is_blank( $t_email ) ) {
-		email_store( $t_email, $t_subject, $t_message, null, true );
+		$t_params = array('admin_name' => $p_admin_name, 'user_id' => $p_user_id, 'confirm_hash' => $p_confirm_hash);
+		email_store( $t_email, $t_subject, $t_message, 'email_notification_signup', $t_params, null, true );
 		log_event( LOG_EMAIL, 'Signup Email = %s, Hash = %s, User = @U%d', $t_email, $p_confirm_hash, $p_user_id );
 	}
 
@@ -569,7 +570,8 @@
 	# Send password reset regardless of mail notification preferences
 	# or else users won't be able to receive their reset passwords
 	if( !is_blank( $t_email ) ) {
-		email_store( $t_email, $t_subject, $t_message, null, true );
+		$t_params = array('user_id' => $p_user_id, 'confirm_hash' => $p_confirm_hash);
+		email_store( $t_email, $t_subject, $t_message, 'email_notification_forgotten_password', $t_params, null, true );
 		log_event( LOG_EMAIL, 'Password reset for user @U%d sent to %s', $p_user_id, $t_email );
 	} else {
 		log_event( LOG_EMAIL, 'Password reset for user @U%d not sent, email is empty', $p_user_id );
@@ -602,7 +604,7 @@
 		$t_message = lang_get( 'new_account_signup_msg' ) . "\n\n" . lang_get( 'new_account_username' ) . ' ' . $p_username . "\n" . lang_get( 'new_account_email' ) . ' ' . $p_email . "\n" . lang_get( 'new_account_IP' ) . ' ' . $_SERVER['REMOTE_ADDR'] . "\n" . config_get_global( 'path' ) . "\n\n" . lang_get( 'new_account_do_not_reply' );
 
 		if( !is_blank( $t_recipient_email ) ) {
-			email_store( $t_recipient_email, $t_subject, $t_message );
+			email_store( $t_email, $t_subject, $t_message, 'email_notification_new_account' );
 			log_event( LOG_EMAIL, 'New Account Notify for email = \'%s\'', $t_recipient_email );
 		}
 
@@ -1141,7 +1143,7 @@
  *                             even when using cronjob
  * @return integer|null
  */
-function email_store( $p_recipient, $p_subject, $p_message, array $p_headers = null, $p_force = false ) {
+function email_store(  $p_recipient, $p_subject, $p_message, $p_message_id = null, $p_params = null, array $p_headers = null, $p_force = false ) {
 	global $g_email_shutdown_processing;
 
 	$t_recipient = trim( $p_recipient );
@@ -1176,6 +1178,8 @@
 	}
 	$t_email_data->metadata['hostname'] = $t_hostname;
 
+	$t_email_data = event_signal('EVENT_NOTIFY_EMAIL', $t_email_data, array( 'message_id' => $p_message_id, 'params' => $p_params,));
+
 	$t_email_id = email_queue_add( $t_email_data );
 
 	# Set the email processing flag for the shutdown function
@@ -1322,7 +1326,7 @@
 		$t_mail->DKIM_identity = config_get( 'email_dkim_identity' );
 	}
 
-	$t_mail->IsHTML( false );              # set email format to plain text
+	$t_mail->IsHTML( isset( $t_email_data->metadata['Content-Type'] ) && stripos( $t_email_data->metadata['Content-Type'], "text/html" ) !== false );
 	$t_mail->WordWrap = 80;              # set word wrap to 80 characters
 	$t_mail->CharSet = $t_email_data->metadata['charset'];
 	$t_mail->Host = config_get( 'smtp_host' );
@@ -1504,7 +1508,8 @@
 		$t_header = "\n" . lang_get( 'on_date' ) . ' ' . $t_date . ', ' . $t_sender . ' ' . $t_sender_email . lang_get( 'sent_you_this_reminder_about' ) . ': ' . "\n\n";
 		$t_contents = $t_header . string_get_bug_view_url_with_fqdn( $p_bug_id ) . " \n\n" . $p_message;
 
-		$t_id = email_store( $t_email, $t_subject, $t_contents );
+		$t_params = array( 'message' => $p_message, 'bug_id' => $p_bug_id, 'recipient' => $t_recipient, 'sender' => $t_sender, 'sender_email' => $t_sender_email );
+		$t_id = email_store( $t_email, $t_subject, $t_contents,'email_bug_reminder', $t_params );
 		if( $t_id !== null ) {
 			$t_result[] = $t_recipient;
 		}
@@ -1639,7 +1644,7 @@
 	}
 
 	# send mail
-	email_store( $t_user_email, $t_subject, $t_message, $t_mail_headers );
+	email_store( $t_user_email, $t_subject, $t_message, $p_message_id, array_merge($p_visible_bug_data, array('header_optional_params' => $p_header_optional_params)), $t_mail_headers);
 
 	return;
 }
diff -ruN old/core/events_inc.php new/core/events_inc.php
--- old/core/events_inc.php	2018-07-16 23:57:54.820800300 +0200
+++ new/core/events_inc.php	2018-07-16 23:56:54.965800300 +0200
@@ -139,7 +139,8 @@
 	# Email notification events
 	'EVENT_NOTIFY_USER_INCLUDE' => EVENT_TYPE_DEFAULT,
 	'EVENT_NOTIFY_USER_EXCLUDE' => EVENT_TYPE_DEFAULT,
-
+	'EVENT_NOTIFY_EMAIL' => EVENT_TYPE_CHAIN,
+	
 	# Wiki events
 	'EVENT_WIKI_INIT' => EVENT_TYPE_FIRST,
 	'EVENT_WIKI_LINK_BUG' => EVENT_TYPE_FIRST,
diff -ruN old/manage_user_update.php new/manage_user_update.php
--- old/manage_user_update.php	2018-07-16 23:53:57.906800300 +0200
+++ new/manage_user_update.php	2018-07-16 23:55:26.088800300 +0200
@@ -205,7 +205,7 @@
 		$t_updated_msg = lang_get( 'email_user_updated_msg' );
 		$t_message = $t_updated_msg . "\n\n" . config_get_global( 'path' ) . 'account_page.php' . "\n\n" . $t_changes;
 
-		if( null === email_store( $t_email, $t_subject, $t_message ) ) {
+		if( null === email_store( $f_email, $t_subject, $t_message, 'email_notification_user_update', array( 'changes' => $t_changes ) )  ) {
 			log_event( LOG_EMAIL, 'Notification was NOT sent to ' . $f_username );
 		} else {
 			log_event( LOG_EMAIL, 'Account update notification sent to ' . $f_username . ' (' . $t_email . ')' );