Unless you go for HAM radio or into FM DX there are not a lot of options anymore to receive a QSL from Belgium. Fortunately Oostende Radio is still a reliable verifier. I received this QSL Oostende Radio 518 kHz for my reception of their NAVTEX message announcing gunnery exercises on the North Sea:

2023-04-21 07:10:10> ZCZC TA63
2023-04-21 07:10:12> 210611 UTC APR
2023-04-21 07:10:16> OOSTENDERADIO MSI 187/23
2023-04-21 07:10:20> DE PANNE-OOSTENDE
2023-04-21 07:10:27> GUNNERY EXERCISES IN THE MIDDLE SECTOR OF LOMBARDSIJDE
2023-04-21 07:10:35> TODAY 21 04 2023 FROM 0630 UNTIL 1030 UTC.
2023-04-21 07:10:43> GUNNERY SECTOR IS LISTENING ON CHAN 16 AND 67.
2023-04-21 07:10:49> CANCEL THIS MSG 211030 UTC APR.
2023-04-21 07:10:49> NNNN

Reading the letter I somehow got the feeling that they forgot to include the QSL card. So I “copied” one from Hugo’s DX hoekje… ­čśë

QSL Oostende Coastal Radio NAVTEX
QSL Letter Oostende Radio, Belgium
QSL Oostende Radio OSU, Belgium (taken from Hugo’s DX hoekje)