Acknowledgements

Apache Software

ZixCorp software includes software developed by the Apache Software Foundation (http://www.apache.org/) under the license terms described in http://www.apache.org/LICENSE, http://jakarta.apache.org/LICENSE, http://xml.apache.org/LICENSE, and http://xml.apache.org/xalan-j/index.html#license.

Cygwin

ZixCorp software uses cygwin distributed under the GNU General Public License (http://cygwin.com/COPYING). The source code of cygwin can be downloaded from http://www.cygwin.com/ or obtained by writing to the ZixCorp Legal Department, 2711 N. Haskell Ave., Suite 2200, LB 36, Dallas, TX 75204-2960 and reference “Request for cygwin source code” with a $10 check or money order (made payable to Zix Corporation) to cover the media and shipping/handling costs.

dtSearch

ZixGateway service uses software provided under license from dtSearch (www.dtsearch.com) to provide the content pattern matching functionality.

JDOM

ZixCorp software also includes software developed by the JDOM Project (http://www.jdom.org/) under the license terms described in http://www.jdom.org/docs/faq.html#a0030.

OpenSSL

ZixCorp software also includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/) and cryptographic software written by Eric Young (eay@cryptsoft.com), under the license terms described in http://www.iona.com/support/docs/e2a/asp/5.0/corba/ssl/html/LicensesAppx2.html.

PGP

ZixGateway service uses the OpenPGP Gateway, which uses the GnuPG, GnuPGME and GMime libraries that are free software distributed under the terms of the GNU Lesser General Public License version 2.1 as published by Free Software Foundation, Inc.  These libraries are distributed WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details (http://www.gnu.org/copyleft/lesser.html). The GnuPGME library has been modified for this application and the source code for the modified GnuPGME library is available upon request. The request should be in writing and should be sent to the ZixCorp Legal Department, 2711 N. Haskell Avenue, Suite 2200, LB 36, Dallas, Texas 75204-2960 with a $10 check or money order (made payable to Zix Corporation) to cover the media and shipping/handling costs.

Postfix

ZixCorp software also uses postfix under license terms described in http://www.ibm.com/developerworks/opensource/library/os-i18n2/os-ipl.html. The source code of postfix is available free of charge at http://www.postfix.org/.

RSA

Hash functions used in ZixCorp software are derived from the RSA Data Security, Inc., MD-5 Message-Digest Algorithms.

Sophos

Certain of the the ZixCorp secure e-messaging services incorporate virus detection functionality provided by Sophos Plc. (www.sophos.com) and anti-spam functionality provided by Lyris Technologies (www.lyris.com).

The Sentry

ZixCorp software incorporates spell-checking code from The Sentry Spelling-Checker Engine, copyright (c) 1999 WintertreeSoftware, Inc.

Tumbleweed

Some of the processes, arrangements, user interfaces, transaction sequences, site and system architectures, data arrangements, and data processing algorithms, described or embodied in our products and services, may be covered by one or more of the following U.S. Patents Nos. 5,790,790; 6,061,448; 6,192,407; and 6,609,196 owned by Tumbleweed Communications Corp. ZixCorp holds a license to these patents.

Other Open Source

In addition, ZixCorp software uses the following open source software under the licensing terms described in the corresponding file indicated below: