Public Folder Creator Issue

Hello.

After migration from Exchange 2003 to 2010 I've found a problem with Mail enabled Public Folder.

The message delivered to PF now have property 0x3FF8001F PR_CREATOR_NAME = domain\HUB_NAME$, not %username%. So permission "edit own" and "delete own" don't work and users can't change or delete their messages. The messages that had been delivered to Exchange 2003 have this property = %username%

Hub server installed on different server from mailbox.

What is wrong with mail flow?

Thanks.