Exhibit 99.3

Email to Employees

To my fellow Catalyst employees:

Just a few moments ago, we publically announced that we have entered into a definitive merger agreement with SXC Health Solutions Corp that will combine our companies in a cash and stock transaction valued at approximately $4.4 billion. This is an exciting development for our company and I want to tell you a little bit about what this means for Catalyst.

The combination of these two organizations will bring together the industry leading pharmacy tools and technology expertise of SXC with Catalyst’s best-in-class PBM services and clinical offerings. Upon completion of the transaction, which we expect to happen in the second half of 2012, the combined companies will cover approximately 25 million members, with annual prescription volume of more than 200 million adjusted PBM scripts.

At this point in the process, work begins to obtain the regulatory and shareholder approvals necessary to close this transaction. Until that time, SXC and Catalyst will continue to operate as independent companies and compete vigorously – today’s announcement will have no impact on our day-to-day operations and it remains business as usual at Catalyst. Even when the merger closes, rest assured that the core elements of our value proposition will remain intact. Our unbiased, client-centered philosophy will only be strengthened by this move and we will continue to operate with the same guiding principles that have made us who we are today.

I have no doubt that many of you will have questions about this decision and what impact it will have on you. To help answer those questions, we will be hosting a Town Hall meeting at 1:00 p.m. ET/12:00 p.m. CT/10:00 a.m. PT to discuss the combination and answer any questions that you may have. For our employees in Rockville, we will be meeting in-person in the conference center at 702 King Farm Boulevard and senior leaders will be present in several of our other locations to dial-in to the meeting. I encourage all of you to join leadership in the conference room of your office to participate in the meeting. For remote employees, we will provide dial-in information later this morning. In addition, we have prepared the attached Employee FAQs, which will also be posted on the homepage of the Catalyst Intranet site. While we are still in the early stages of this process, we will continue to keep you informed as we move forward.

It is likely that this transaction will generate interest from the media and other third parties, and it is important for us to speak with one voice. If you receive any inquiries from the media or other questions from outside Catalyst, please forward them to Chris Burns, our Senior Vice President of Marketing at (773) 505-1762 or cburns@catalystrx.com.

The key to the success of our business has been — and will continue to be —you, our valued employees. I hope you share my enthusiasm about this exciting transaction. I want to thank all of you for your continued diligence, support and focus on serving our clients and members.

Sincerely

David

Catalyst Forward Looking Statements

Certain statements included herein may contain certain forward-looking statements including, without limitation, statements concerning Catalyst’s operations, economic performance and financial condition. The words “believe,” “expect,” “anticipate,” “will,” “could,” “would,” “should,” “may,” “plan,” “estimate,” “intend,” “predict,” “potential,” “continue,” and the negatives of these words and other similar expressions generally identify forward-looking statements. In addition to Catalyst’s expectations or estimates of a combined company’s future performance or matters relating to the proposed transaction, these forward-looking statements may include statements addressing Catalyst’s operations and Catalyst’s financial performance. Readers are cautioned not to place undue reliance on these forward-looking statements, which, among other things, speak only as of their dates. These forward-looking statements are based largely on Catalyst’s current expectations and are based on a number of risks and uncertainties, including, without limitation, (i) general adverse economic conditions, (ii) changes in governmental laws and regulations, (iii) Catalyst’s ability to compete effectively in the pharmacy benefit management industry, (iv) Catalyst’s relationships with key clients, pharmacy network affiliations and various pharmaceutical manufacturers and rebate intermediaries, (v) changes in industry pricing benchmarks, (vi) uncertainties relating to the transition and integration of completed and future acquisitions and/or expansion opportunities, (vii) Catalyst’s current level of indebtedness and any future indebtedness Catalyst may incur; (viii) disruption in Catalyst’s operations, (ix) unanticipated changes in Catalyst’s ability to execute its growth strategy, (x) generic utilization levels, (xi) insufficient insurance coverage to cover costs associated with litigation, (xii) Catalyst’s ability to accurately estimate how much future revenue Catalyst will generate, as well as the level of implementation and transaction costs that Catalyst will incur, under newly commenced PBM agreements and other risks and uncertainties discussed in Catalyst’s filings with the SEC, including Catalyst’s Annual Report on Form 10-K and quarterly reports on Form 10-Q. Actual results could differ materially from results referred to in the forward-looking statements. In light of these risks and uncertainties, there can be no assurances that the results referred to in the forward-looking statements contained herein will, in fact, occur. Catalyst undertakes no

obligation to revise any forward-looking statements in order to reflect events or circumstances that may arise after the date hereof. Readers are urged to carefully review and consider the various disclosures made in Catalyst’s other filings with the SEC that attempt to advise interested parties of the risks and factors that may affect Catalyst’s business.

Transaction Forward-Looking Statements

In addition, numerous factors could cause actual results with respect to the proposed transaction to differ materially from those in the forward-looking statements, including without limitation, the possibility that the expected efficiencies and cost savings from the proposed transaction will not be realized, or will not be realized within the expected time period; the risk that the SXC and Catalyst businesses will not be integrated successfully; the ability to obtain governmental approvals of the proposed transaction on the proposed terms and schedule contemplated by the parties; the failure of shareholders of SXC or Catalyst to approve the proposed transaction; disruption from the proposed transaction making it more difficult to maintain business and operational relationships; the risk of customer attrition; the possibility that the proposed transaction does not close, including, but not limited to, due to the failure to satisfy the closing conditions; and the ability to obtain the financing contemplated to fund a portion of the consideration to be paid in the proposed transaction and the terms of such financing.

Important Additional Information

This communication does not constitute an offer to sell or the solicitation of an offer to buy any securities or a solicitation of any vote or approval. This communication is being made in respect of the proposed transaction involving Catalyst and SXC. The proposed transaction will be submitted to the shareholders of Catalyst and the shareholders of SXC for their consideration. In connection therewith, the parties intend to file relevant materials with the SEC, including a joint proxy statement/prospectus that will be mailed to shareholders. Such documents, however, are not currently available. BEFORE MAKING ANY VOTING OR INVESTMENT DECISIONS, INVESTORS AND SECURITY HOLDERS OF CATALYST AND/OR SXC ARE URGED TO READ THE JOINT PROXY STATEMENT/PROSPECTUS REGARDING THE PROPOSED TRANSACTION AND ANY OTHER RELEVANT DOCUMENTS THAT WILL BE FILED WITH THE SEC CAREFULLY AND IN THEIR ENTIRETY WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE PROPOSED TRANSACTION. Investors and security holders may obtain free copies of the proxy statement/prospectus and other documents containing important information about Catalyst and SXC, once such documents are filed with the SEC, through the website maintained by the SEC at www.sec.gov. Copies of the documents filed with the SEC by SXC will be available free of charge on SXC’s website at www.sxc.com under the heading “Investor Information” or by contacting SXC’s Investor Relations Department at 630-577-3100. Copies of the documents filed with the SEC by Catalyst will be available free of charge on Catalyst’s website at www.catalysthealthsolutions.com under the heading “Investor Information” or by contacting Catalyst’s Investor Relations Department at 301-548-2900.

SXC, Catalyst and certain of their respective directors, executive officers and other members of management and employees may be deemed to be participants in the solicitation of proxies in connection with the proposed transaction. Information about the directors and executive officers of SXC is set forth in its proxy statement for its 2012 annual meeting of stockholders, which was filed with the SEC on April 2, 2012. Information about the directors and executive officers of Catalyst is set forth in its proxy statement for its 2011 annual meeting of shareholders, which was filed with the SEC on April 28, 2011. These documents can be obtained free of charge from the sources indicated above. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the joint proxy statement/prospectus and other relevant materials to be filed with the SEC when they become available.