certified mail

US uncountable

(US) First class mail that provides the sender proof of mailing and a delivery record.

Japanese Meaning

送付証明および配達記録が提供される一等郵便サービス

I mailed the signed contract by certified mail to make sure we had proof that it was delivered.

署名済みの契約書は、発送証明と配達記録が得られる郵便で送付しました。

Sense（1）

(US) First class mail that provides the sender proof of mailing and a delivery record.