Foreign executors, administrators and guardians may satisfy mortgages upon the records of any county in this state, upon producing and recording in the office of the county recorder of the county in which such mortgage is recorded, a duly certified and authenticated copy of their letters testamentary, or of administration or of guardianship, and which certificate or authentication shall also recite that said letters have not been revoked. For the purposes of this section, “guardian” includes a foreign conservator, committee, or comparable fiduciary.