EX-99.3

Exhibit 99.3

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EXTRAORDINARY GENERAL MEETING OF SHAREHOLDERS OF INTERXION HOLDING N.V. February 27, 2020 GO GREEN e-Consent makes it easy to go paperless. With e-Consent, you can quickly access your proxy material, statements and other eligible documents online, while reducing costs, clutter and paper waste. Enroll today via www.astfinancial.com to enjoy online access. NOTICE OF INTERNET AVAILABILITY OF PROXY MATERIAL: The Notice of Meeting, proxy statement and proxy card are available at www.interxion.com Please sign, date and mail your proxy card in the envelope provided as soon as possible. Please detach along perforated line and mail in the envelope provided. 00033330030300300000 7 022720 WHEN PROPERLY EXECUTED, THIS PROXY WILL BE VOTED IN THE MANNER DIRECTED HEREIN BY THE UNDERSIGNED SHAREHOLDER. IF NO DIRECTION IS MADE, THIS PROXY WILL BE VOTED FOR EACH OF THE FOLLOWING PROPOSALS. PLEASE SIGN, DATE AND RETURN PROMPTLY IN THE ENCLOSED ENVELOPE. PLEASE MARK YOUR VOTE IN BLUE OR BLACK INK AS SHOWN HERE Said attorneys and proxies, or their substitutes, at said meeting, or any adjournments thereof, may exercise all of the powers hereby given. Any proxy heretofore given is hereby revoked. Receipt is acknowledged of the Notice of Extraordinary General Meeting and the Proxy Statement accompanying such Notice. Each of the capitalized terms herein has the meaning given to it in the Purchase Agreement, dated as of October 29, 2019, between InterXion Holding N.V. (the“Company”), Digital Intrepid Holding B.V. (formerly known as DN 39J 7A B.V.) and Digital Realty Trust, Inc. Proposal; 1. To approve the Legal Merger in accordance with the Legal Merger Proposal; 2. Proposal; To approve the Legal Demerger in accordance with the Legal Demerger 3. To approve (A) the Asset Sale and (B) the Post-Demerger Share Sale; 4. To approve (A) the dissolution of the Company, (B) the appointment of Stichting Vereffening InterXion (a foundation under Dutch law) as liquidator of the Company and approval of reimbursement of the Liquidator’s reasonable salary and costs, and (C) the appointment of Intrepid Midco B.V., an affiliate of Buyer, as the custodian of the books and records of the Company in accordance with Section 2:24 of the Dutch Civil Code; 5. To grant full and final discharge to each member of the Company’s Board for their acts of management or supervision, as applicable, up to the date of the Extraordinary General Meeting; 6. To approve the proposed conversion into a private company with limited liability (een besloten vennootschap met beperkte aansprakelijkheid) and amendment of the articles of association of the Company as set forth in Annex C of the proxy statement and to authorize each lawyer, paralegal and (prospective) civil law notary at De Brauw Blackstone Westbroek N.V. in Amsterdam, to execute the deed of conversion and amendment of the articles of association of the Company; and 7. To appoint the following nominees: (i) Jeff Tapley as executive director, and (ii) Andrew P. Power, (iii) Gregory S. Wright and (iv) Joshua A. Mills, as non-executive members of the Company’s Board to replace the resigning directors of the Company’s Board. To change the address on your account, please check the box at right and indicate your new address in the address space above. Please note that changes to the registered name(s) on the account may not be submitted via this method. Signature of Shareholder Date: Signature of Shareholder Date: Note: Please sign exactly as your name or names appear on this Proxy. When shares are held jointly, each holder should sign. When signing as executor, administrator, attorney, trustee or guardian, please give full title as such. If the signer is a corporation, please sign full corporate name by duly authorized officer, giving full title as such. If signer is a partnership, please sign in partnership name by authorized person.