undeliverable
adj. 无法投递的；无法送达的
例句
Undeliverable, returned to sender.
无法投递，退回原处。
《新英汉大辞典》
The E-mail you sent yesterday was returned as undeliverable.
你昨天发的邮件被退回来了。
Message undeliverable. Make sure the SMS address was entered correctly and try again.
无法递送短消息。请确保短消息服务地址输入正确，然后再试。
