My preferred method of sending QSLs is via the bureau. When I really need a card for a new country or a new band-country I tend to send my card directly including one or two IRCs and an addressed envelope.
After the SAC contest in September I sent a few by mail and the answers have already started to drop down in my mailbox. I have received cards from 4X0A (Israel) and EA6AZ (Balearic Islands). 4X0A is the contest call of Jan 4X1VF and the backside of the card is correctly labeled 4X0A.
I worked EA6AZ on 20m and 15m and 4X0A on 15m. That gave me 3 new band-countries. Thanks to both Jan and Tano!
10m FT8 tomorrow
3 hours ago