Del. Code tit. 9 § 8750
If the property attached is in whole or in part real estate, the court making the order for the sale of property shall also order that notice be given to all persons holding liens and encumbrances against the real estate, as set out in the petition of the plaintiff but the failure to include in the petition or in the order the name of any person holding any such lien or encumbrance or the failure to give such notice to such person shall not be sufficient cause to set aside such sale, but the real estate so sold shall not be sold or discharged of liens and encumbrances existing against it held by any person not named in the order and not served with the notice. The notice shall be served personally upon such persons holding liens at least 6 days before the day of sale, by delivering to each of such persons a copy of the order of sale or by leaving a copy thereof at the usual place of abode of such persons within New Castle County in the presence of an adult person. In case it appears to the court that any of such persons holding liens has no known place of abode within New Castle County and cannot be served personally, the court shall order that publication of notice of the sale be made in such newspaper or newspapers published in New Castle County as shall in the judgment of the court best serve to bring to such person knowledge of the sale.
9 Del. C. § 8750