diff --git a/extension/Documentation/Manual.rst b/extension/Documentation/Manual.rst
index e2fa84391b12ed65177fd52c1f61f451fa6d7310..a03abc647d6032a254bef9970d13d45d03730533 100644
--- a/extension/Documentation/Manual.rst
+++ b/extension/Documentation/Manual.rst
@@ -32,12 +32,14 @@ General
 Installation
 ============
 
-The following features are only tested on linux hosts:
+The following features are only tested / supported on linux hosts:
 
+* General: QFQ is coded to run on Linux hosts, preferable on Debian derivates like Ubuntu.
 * HTML to PDF conversion - command `wkhtmltopdf`.
 * Concatenation of PDF files - command `pdftk`.
 * Mime type detection for uploads - command `file`.
 
+
 .. _`preparation`:
 
 Preparation
@@ -108,6 +110,10 @@ Typosript) from specific IPs **or** if a FE-User is logged in.
 
 If there are problems with converting/downloading FE_GROUP protected pages, check `SHOW_DEBUG_INFO = download` to debug.
 
+**Important**: Converting HTML to PDF gives no error message but RC=-1? Check carefully all includes of CSS, JS, images
+and so on! Typically some of them fails to load and wkhtml stops running!
+
+
 HTML to PDF conversion
 ''''''''''''''''''''''
 
@@ -133,6 +139,20 @@ Typoscript code to implement a print link on every page::
 		data = page:uid
 	}
 
+Send Email
+^^^^^^^^^^
+
+QFQ sends mail via `sendEmail` http://caspian.dotconf.net/menu/Software/SendEmail/ - a small perl script without a central
+configuration.
+
+By default, `sendEmail` uses the local installed MTA, writes a logfile to `typo3conf/mail.log` and handles attachments
+via commandline options. A basic HTML email support is implemented.
+
+The latest version is v1.56, which has at least one bug. That one is patched in the QFQ internal version v1.56p1 (see
+QFQ GIT sources in directory 'patches/sendEmail.patch').
+
+The Typo3 sendmail eco-system is not used at all.
+
 Setup
 -----
 
@@ -382,7 +402,7 @@ Example: *typo3conf/config.qfq.ini*
 	DB_1_NAME = qfq_db
 	DB_INIT = set names utf8
 	; DB_INDEX_DATA = 1
-   ; DB_INDEX_QFQ = 1
+	; DB_INDEX_QFQ = 1
 	; SQL_LOG = sql.log
 	; SQL_LOG_MODE = modify
 	; SHOW_DEBUG_INFO = auto
@@ -450,8 +470,8 @@ Example: *typo3conf/config.qfq.ini*
 	;DOCUMENTATION_QFQ = https://docs.typo3.org/typo3cms/drafts/github/T3DocumentationStarter/Public-Info-053/Manual.html
 
 	;FILL_STORE_SYSTEM_BY_SQL_1 = 'SELECT s.id AS periodId FROM Period AS s WHERE s.start<=NOW() ORDER BY s.start DESC LIMIT 1'
-   ; Important: only define an error message, if QFQ should stop running in case of an error or not exact 1 record.
-   ;FILL_STORE_SYSTEM_BY_SQL_ERROR_MSG_1 = No current period found
+	; Important: only define an error message, if QFQ should stop running in case of an error or not exact 1 record.
+	;FILL_STORE_SYSTEM_BY_SQL_ERROR_MSG_1 = No current period found
 
 	;FORM_LANGUAGE_A_ID = 1
 	;FORM_LANGUAGE_A_LABEL = english
@@ -5018,7 +5038,7 @@ Example `_pdf`, `_zip`: ::
 
 ..
 
-Use the `--print-media-type` as wkthml option to access the page with media type 'printer'. Depending on the website
+Use the `--print-media-type` as wkhtml option to access the page with media type 'printer'. Depending on the website
 configuration this switches off navigation and background images.
 
 Rendering 'official' look-alike PDF letters
diff --git a/extension/qfq/qfq/Constants.php b/extension/qfq/qfq/Constants.php
index f7eb2d1f1e01305bcdadd966973f922c667aa872..a0b648f8a78aa0632e7310813260dcfdd029f4c6 100644
--- a/extension/qfq/qfq/Constants.php
+++ b/extension/qfq/qfq/Constants.php
@@ -276,6 +276,9 @@ const ERROR_MISSING_SESSIONNAME = 2400;
 const ERROR_QFQ_SESSION_MISSING = 2401;
 const ERROR_SESSION_BROKEN_SCRIPT_PATH = 2402;
 
+const ERROR_HTML2PDF_MISSING_CONFIG = 2500;
+const ERROR_HTML2PDF_WKHTML_NOT_EXECUTABLE = 2501;
+const ERROR_HTML2PDF_WKHTML_FAILED = 2502;
 //
 // Store Names: Identifier
 //
diff --git a/extension/qfq/qfq/report/Html2Pdf.php b/extension/qfq/qfq/report/Html2Pdf.php
index b9f12488245dbe50a8d1b70c12e7cd7d02ef34dc..df5fafc40bddb6e79fd1f79864713d945e12f5c7 100644
--- a/extension/qfq/qfq/report/Html2Pdf.php
+++ b/extension/qfq/qfq/report/Html2Pdf.php
@@ -67,15 +67,15 @@ class Html2Pdf {
         $this->config = $config;
 
         if (!isset($config[SYSTEM_BASE_URL_PRINT]) || $config[SYSTEM_BASE_URL_PRINT] == '') {
-            throw new \exception(CONFIG_INI . ' - Missing ' . SYSTEM_BASE_URL_PRINT);
+            throw new \exception(CONFIG_INI . ' - Missing ' . SYSTEM_BASE_URL_PRINT, ERROR_HTML2PDF_MISSING_CONFIG);
         }
 
         if (!isset($config[SYSTEM_WKHTMLTOPDF]) || $config[SYSTEM_WKHTMLTOPDF] == '') {
-            throw new \exception(CONFIG_INI . ' - Missing ' . SYSTEM_WKHTMLTOPDF);
+            throw new \exception(CONFIG_INI . ' - Missing ' . SYSTEM_WKHTMLTOPDF, ERROR_HTML2PDF_MISSING_CONFIG);
         }
 
         if (!is_executable($config[SYSTEM_WKHTMLTOPDF])) {
-            throw new \exception(CONFIG_INI . ' - ' . SYSTEM_WKHTMLTOPDF . '=' . $config[SYSTEM_WKHTMLTOPDF] . ' - not found or not executable.');
+            throw new \exception(CONFIG_INI . ' - ' . SYSTEM_WKHTMLTOPDF . '=' . $config[SYSTEM_WKHTMLTOPDF] . ' - not found or not executable.', ERROR_HTML2PDF_WKHTML_NOT_EXECUTABLE);
         }
 
         $this->session = Session::getInstance($phpUnit);
@@ -226,7 +226,8 @@ class Html2Pdf {
         $line = system($cmd, $rc);
 
         if ($rc != 0) {
-            throw new \exception("Error [RC=$rc] $line: $cmd");
+            throw new \exception("Error [RC=$rc] $line: $cmd - in case of trouble: check carefully that *all* CSS, JS, " .
+                "images are accessible. 'wkhtml' does not report problems but fails.", ERROR_HTML2PDF_WKHTML_FAILED);
         }
 
         return $filename;