Cyrus 3.0.4 - Over quota returns 550-Mailbox unknown

[Maros Vegh]

Hello,

i'm using compiled cyrus version 3.0.4 on Debian 9.2.

When the Postfix server is trying to deliver a message via lmtp to cyrus 
mailbox which is over quota, it receives the 550-Mailbox unknown return 
code and not the 452 or 552 Over quota.

In the previous version 2.5.10 it worked fine with default values in 
imapd.conf

Is it a bug or my fault?

Thanks

Maros Vegh