During my stay on a campsite in the north of the Netherlands I enjoyed good conditions on 12 MHz in a relatively noise free environment. That resulted in the reception of a lot of new DSC stations. SHN (Servicio de Hidrografia Naval) in Buenos Aires, Argentina, was one of those!
The email reply took hours only and was the shortest possible. But it carried the three key letters: “QSL”! (I added their logo to the email myself to improve the appearance of this post).
I sent my report to email@example.com. Confirmation followed via firstname.lastname@example.org, which is probably the Coast Guard branch.