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

This Agreement is between Licensor and You. 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, Licensor hereby grants You a royalty-free, perpetual, worldwide, sublicensable, 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(s)" means Yahoo, Inc. ("Yahoo!"), Licensor, and/or any other individual or entity who distributes Implementations under this Agreement.

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. "Licensor" means Yahoo! or any other individual or entity that elects to use this Agreement to license Yahoo! Patent Claims to any licensee.

2.4. "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

2.5. "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 U.S. Patent Application Ser. Nos. 10/671,319, filed Sep. 24, 2003, or 10/805,181, filed Mar. 19, 2004.

2.6. "You" or "Your" means an individual, company, or other legal entity exercising any rights under this Agreement. Any individual who accepts the terms and conditions of 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!, any other DomainKeys Developer or any of their respective licensees under Section 3.4, a patent infringement claim based on the manufacture, use, sale, offer for sale and/or importation of any Implementations ("Implementation IP Claim").

3.2. To indicate your assent to the terms and conditions of this Agreement and in order to obtain a license to make, use, sell, offer for sale, and/or import Implementations, You must include, attach or preserve the following prominently displayed statement in the source code and object code of any such Implementations: "This code incorporates intellectual property owned by Yahoo! and licensed pursuant to the Yahoo! DomainKeys Patent License Agreement.".

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

3.4. You may choose to distribute Implementations under this Agreement or a different agreement, provided that:

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

(b) if distributed under a different agreement, such different agreement contains terms and conditions that (i) provide no fewer rights, privileges and immunities to DomainKeys Developers than the terms and conditions of this Agreement, including, without limitation, Sections 1.1, 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 restriction 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 and at its sole discretion, update or modify the terms of this Agreement. If Yahoo! makes any such modifications, 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. 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 any licensees of any DomainKeys Developer; 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 that involve Yahoo! as a party 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.

3.9. In the event that any provision of this Agreement is deemed to be invalid, such invalidity shall not affect the remainder of this Agreement.

4. LEGAL DISCLAIMERS.

4.1. THE YAHOO! PATENT CLAIMS, THIS AGREEMENT, THE DOMAINKEYS TRADEMARK, AND THE 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 DomainKeys Developers 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, trademark or other intellectual property rights of any other entity. 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.

4.3. DOMAINKEYS DEVELOPERS 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, AND EVEN IF THE REMEDIES PROVIDED FOR IN THIS AGREEMENT FAIL OF THEIR ESSENTIAL PURPOSE.