Del. Code tit. 12 § 1506
In case of the grant of letters testamentary or of administration, the person designated as an executor or administrator, if a nondomiciliary, or if a corporation not incorporated under the laws of Delaware, shall file in the office of the Register of Wills granting such letters, before the issuance of the letters, an irrevocable power of attorney designating that Register and the Register's successors in office as the person upon whom all notices and process issued by any court in this State may be served, with like effect as personal service in relation to any suit, matter, cause or thing affecting or pertinent to the estate in which the letters are issued. The Register shall forward forthwith, by certified mail, return receipt requested, to the address of such executor or administrator, which shall be stated in the power of attorney, any notices or process served upon the Register.
12 Del. C. § 1506