add email autoconfig

.well-known/autoconfig/mail/config-v1.1-xml

+<?xml version="1.0" encoding="UTF-8"?>
+<clientConfig version="1.1">
+  <emailProvider id="cccv">
+    <domain>cccv.de</domain>
+    <displayName>cccv.de</displayName>
+    <displayShortName>cccv</displayShortName>
+    <incomingServer type="imap">
+      <hostname>imap.cccv.de</hostname>
+      <port>993</port>
+      <socketType>SSL</socketType>
+      <authentication>password-cleartext</authentication>
+      <username>%EMAILLOCALPART%</username>
+    </incomingServer>
+    <outgoingServer type="smtp">
+      <hostname>mail.cccv.de</hostname>
+      <port>587</port>
+      <socketType>STARTTLS</socketType>
+      <authentication>password-cleartext</authentication>
+      <username>%EMAILLOCALPART%</username>
+    </outgoingServer>
+    <documentation url="https://docs.cccv.de/#mail">
+      <descr lang="de">Dokumentation</descr>
+      <descr lang="en">Documentation</descr>
+    </documentation>
+  </emailProvider>
+</clientConfig>