diff --git a/convert.sh b/convert.sh
index a59fd500..9b6d8da1 100644
--- a/convert.sh
+++ b/convert.sh
@@ -68,8 +68,10 @@ for chapter_dir in ${all_chapter_dirs}; do
         echo -e "### ${_chapter_title}" >> ${INDEX_MD}
 
         if [ -f ${_summary_md} ]; then
-            _chapter_summary="$(cat ${_summary_md})"
-            echo -e "${_chapter_summary}" >> ${INDEX_MD}
+            cat ${_summary_md} >> ${INDEX_MD}
+
+            # Insert an empty line to not mess up other formats like list.
+            echo '' >> ${INDEX_MD}
         fi
     fi
 
diff --git a/html/index.html b/html/index.html
index a77b707d..59e2ccf8 100644
--- a/html/index.html
+++ b/html/index.html
@@ -31,6 +31,7 @@
 <li><a href="password.hashes.html">Password hashes</a></li>
 </ul>
 <h3 id="configure-mail-client-applications">Configure mail client applications</h3>
+<p>If you're using different mail clients, please help write documents to guide other users to setup the mail clients.</p>
 <ul>
 <li><a href="configure.thunderbird.html">Configure Thunderbird as mail client (POP3/IMAP, SMTP and global ldap address book)</a></li>
 <li><a href="sogo.bb10.caldav.carddav.html">BlackBerry 10: Add calendar (CalDAV) and contact (CardDAV) services</a></li>
diff --git a/mua/_summary.md b/mua/_summary.md
new file mode 100644
index 00000000..1d082e99
--- /dev/null
+++ b/mua/_summary.md
@@ -0,0 +1 @@
+If you're using different mail clients, please help write documents to guide other users to setup the mail clients.