maildirfolder file created in maildir root during auto-creation with 2.3.4.1 but not 2.2.27

Hello,

as the tin says. I have several servers running 2.2.27 (Debian stretch) and am adding new ones with 2.3.4.1 (Debian buster). The configs were upgraded where needed but neither 10-mail.conf nor 15-mailboxes.conf were changed. 15-mailboxes is all commented out (I guess the default is auto-create, which isn't documented anywhere I could find) and the only non-comments in 10-mail.conf are

mail_location = maildir:%h mail_privileged_group = mail

So yes, no namespaces are explicitly defined/declared.

The 2.3.4.1 version wrongly creates a maildirfolder file in the home directory (maildir root), preventing exim from correctly creating/using maildirsize.

a) Is this expected behavior and can it be changed? b) How can I disable inbox auto-creation if a) doesn't pan out?

Thanks,

Christian

Christian Balzer Network/Systems Engineer
chibi@gol.com Rakuten Mobile Inc.