Copyright (c) 2004, Yahoo! Inc.
All rights reserved.

You agree to be bound by all the terms and conditions set forth below and, subject to those terms and conditions, You may use the intellectual property described below.

1. LICENSE GRANT.

1.1. Subject to the terms and conditions of this Agreement, DomainKeys Developer hereby grants You, a royalty-free, worldwide, sub-licensable, non-exclusive license under its rights to the Yahoo! Patent Claims to make, use, sell, offer for sale, and/or import Implementations.

2. DEFINITIONS.

2.1. "DomainKeys Developer" means Yahoo! Inc. ("Yahoo!") or any licensee or sublicensee (direct or indirect) of the Yahoo! Patent Claims.

2.2. "Implementations" means the specific portions of a hardware or software implementation expressly required to be compliant with the Specifications for the sole purpose of a sender verification solution in connection with e-mail.

2.3. "Specifications" means the specification having submission ID "draft-delany-domainkeys-base-01.txt" dated Aug 2004 published through the IETF (Internet Engineering Task Force). The Specifications may be found at the following link:
http://antispam.yahoo.com/domainkeys/draft-delany-domainkeys-base-01.txt

2.4. "Yahoo! Patent Claims" shall mean those claims of all Yahoo! foreign and domestic patents and patent applications that base their priority on U.S. Provisional Patent Application Ser. Nos. 60/497,794, filed Aug. 26, 2003, or 60/553,300, filed Mar. 15, 2004, or Patent Application Ser. Nos. 10/671,319, filed Sep. 24, 2003, or 10/805,181, filed Mar. 19, 2004.

2.5. "You" or "Your" means an individual, company, or other legal entity exercising rights under this Agreement. Any individual exercising rights under this Agreement on behalf of a company or other legal entity represents and warrants that the individual has the authority to enter into this Agreement on behalf of the company or other legal entity.

3. TERMS.

3.1. You agree not to assert against Yahoo!, or any other DomainKeys Developer, a patent infringement claim against any Implementation ("Implementation IP Claim").

3.3. You will not use the name of Yahoo! to endorse or promote any products or Implementations without specific prior written permission of Yahoo!. "DomainKeys" is a trademark of Yahoo!. However, You may state Your Implementation is "DomainKeys compliant", "supports DomainKeys", or is "DomainKeys-enabled", without citation to Yahoo!, but You should create Your own product names or trademarks for Your specific Implementations and the term "DomainKeys" shall not be used by You in or as part of a name for Your specific Implementations.

3.4. You may choose to distribute Implementations under this Agreement or a separate agreement, including without limitation a sublicense agreement, provided that:

(a) such agreement complies with the terms and conditions of this Agreement;

(b) a copy of this Agreement or the separate agreement is included with each copy of the Implementations along with the following prominently displayed statement: "By making, using, selling, offering for sale, and/or importing this product, you agree to the terms and conditions of the Yahoo! DomainKeys Patent License Agreement or other separate agreement contained herein."; and

(c) if distributed under a separate agreement, such separate agreement must contain terms no less protective of DomainKeys Developers than the terms and conditions of this Agreement, including, without limitation, Sections 3.1, 3.4, 3.7, 4.1, 4.2, and 4.3.

3.5. You acknowledge that implementations of the Specifications may be subject to U.S. export jurisdiction and other applicable national and international laws. You agree to comply with all export, re-export, or import restrictions, laws, or regulations.

3.6. Yahoo!, and only Yahoo!, may, from time to time, update or modify the terms of this Agreement. If Yahoo! makes such a modification, You may continue under the terms and conditions of this Agreement or agree to the updated or modified terms and conditions. For the most recent version of this Agreement please contact Yahoo!.

3.7. The term of this Agreement is perpetual unless terminated as set forth below. This Agreement and the rights hereunder will terminate:

(a) automatically without notice from Yahoo!, if You at any time during the term of this Agreement assert any Implementation IP Claim against Yahoo!;

(b) upon written notice from Yahoo!, if You at any time during the term of this Agreement assert any Implementation IP Claim against any DomainKeys Developer other than Yahoo!; or

(c) where (a) or (b) do not apply, automatically without notice from Yahoo!, if You fail to comply with any term(s) of this Agreement and fail to cure such breach within 30 days of You becoming aware of such breach.

3.8. This Agreement constitutes the entire agreement between the parties with respect to the subject matter hereof. This Agreement shall be governed by and construed under the laws of the United States and the State of California without giving effect to California conflict of law provisions or to construction provisions favoring either party. All actions arising out of or relating to this Agreement will be adjudicated exclusively by the Superior Court of the State of California for the County of Santa Clara or the United States District Court for the Northern District of California.

4. LEGAL DISCLAIMERS.

4.1. THE YAHOO! PATENT CLAIMS, THIS AGREEMENT, THE DOMAINKEYS TRADEMARK, AND SPECIFICATIONS ARE PROVIDED ON AN "AS IS" BASIS, WITHOUT REPRESENTATIONS, WARRANTIES OR CONDITIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED INCLUDING, WITHOUT LIMITATION, ANY REPRESENTATIONS, WARRANTIES OR CONDITIONS OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY, OR FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of exercising any rights under this Agreement and using the Specifications and the DomainKeys trademark and assume all risks associated in connection therewith, including, but not limited to, the risks and costs of program errors, compliance with applicable laws, damage to or loss of data, programs or equipment, and unavailability or interruption of operations.

4.2. You expressly acknowledge and agree that no assurances are provided by any DomainKeys Developer with respect to the validity of the Yahoo! Patent Claims or that the Specifications, the DomainKeys trademark or any implementations related to the Specifications or the DomainKeys trademark do not infringe or misappropriate the patent or other intellectual property rights of any other entity. All DomainKeys Developers disclaim any liability to You for claims brought by any other person or entity based on infringement or misappropriation of intellectual property rights or otherwise. As a condition to exercising the rights and licenses granted hereunder, You hereby assume sole responsibility to secure any other intellectual property rights needed, if any.

4.3. DOMAINKEYS DEVELOPER SHALL NOT HAVE ANY LIABILITY FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING WITHOUT LIMITATION LOST PROFITS), HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE EXERCISE OF ANY RIGHTS UNDER THIS AGREEMENT, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.