ToDo
Things, that have to be documented:
- generating the decrypted SSL-key with OpenSSL-CA
 - use of TinyCA and phpki-CA
 - Postfix: main.cf and master.cf
 - implement http://www.contentschmiede.de/archiv/2005/08/26/postfix_fuer_typo3_und_gmx_fit_machen/ in email → Postfix → SMTPd- / SMTP-Authentication