This is likely a situation where the permissions wizard is making a bad assumption based on the thin error values we get back from AD when checking rights.
In this case it's going to check all the mailstores and see if the account you've assigned to be the messaging account has send as/receive as rights explicitly denied on them - this would typically indicate they were a member of one of the groups listed since by default members of those groups are explicitly denied access.
However it could also be that the account you're running the Permissions Wizard under does not have rights to even check the SA/RA rights on the mailstores and we're not picking up on that and throwing up the bogus error message - you can try adding the account you're running as to the Exchange Domain Servers group and then running the permissions wizard again - this will ensure that we have rights to check for Sa/Ra permissions on the mailstores.
Let me know if that helps and we'll work on seeing if we can get a better error message in there when this crops up.
