I sent a letter to Brussels from Brussels, formed in this style:
Attn: <employee name>
<org name>
P.B. <box №> <street>
1030 Brussel
I only added the attn: line to the top. The street probably should have been on the next line. The letter came back 3 months later with this bPost sticker:
“ne reçoit pas/plus le courrier a l’adresse indiquee”
So apparently something is wrong with that address. Whatever the problem, I cannot imagine why it took 3 months for bPost to figure out there was a problem.
The street missing is probably the issue.
About boost, people are using letters less and less, the service is degrading
Hopefully the minor mistake of putting the street name on the same line as the box number is not the issue. The box number is correct but it’s possible that it was erroneously put in the wrong box.
I received election mail promoting a political party 1 week after election day passed. So certainly in that case bPost must have lost the mail somehow then found it. Which correlates with your conjecture that service quality is dropping.