The package was returned because it was not properly address.

address 是动词，意思是"在邮件或包裹上写明收件人的姓名和地址"。 properly 是副词，由形容词 proper（正确的、适当的）加上后缀 -ly 构成，表示"正确地、适当地"。 not properly addressed 表示"没有正确填写地址"。