Originally Posted by
SusanDK
I shall remember this in 9 1/2 years when I next need to renew.

It's good to know for my husband when his U.S. passport is due for renewal in two years. His Danish passport is due next year and we're going to try to have it renewed this year.
My guess is that they would only be willing to return it by mail to a local address, not return it to a U.S. address. But this could still be an option if one has family at the foreign destination as we do, and can have it delivered to them. OTOH, I do hope that the issues with long wait times this year is an anomaly and this isn't the norm for passport issuance in the U.S.
With postage prepaid, the US Embassy in Copenhagen will send it via mail of sort to addresses in at least Denmark and in Sweden. But mail/courier introduces more variability and risk than an in-person pickup. When it comes to unaccompanied passports being sent across borders, there is another chance for a hiccup and why even for the Swedish addresses for applications submitted in Denmark I prefer to have the passports picked up in-person.
The regulation is that the embassy/consulates can only hold the newly-issued passport/passport card for 90 days, or the passport/passport card gets returned to the US. And for those who tend to apply for a passport and passport card at the same time, the embassy/consulate will typically get the passports back at a different/earlier time than the passport card. Just somethings to keep in mind.