[Dovecot] Hardlinking with Sieve

I have a simple Sieve rule to protect me from accidentally deleting mail:

fileinto :copy "backup";

Should I expect this backup to be hardlinked to the ordinary one? Obviously, that would make the backup be almost for free in terms of storage, but currently I do not see any linking.

Using Maildir, by the way, and I have not touched the maildir_copy_with_hardlinks setting.

TIA, Anders.