We have our own Dynamics CRM hosting platform and also switched to Microsoft Online (BPOS) a few months ago.
I configured the Email Router using the excellent blog post on the CRM Team Blog. All was going well but we subsequently discovered that Meeting Requests were not being received. I found that all meeting requests were being diverted into crmadmin’s mailbox.
I had configured Dynamics CRM Email Router to use Delegate Access as discussed in the CRM Team blog post above. This led to the Dynamics CRM Administrator user to be added as a delegate on each user’s mailbox with setting "My Delegates Only". This appears to have caused the problem with meeting requests.
The workaround was to change the Delegate setting to "My Delegates Only, but send a copy of meeting requests and responses to me (recommended)". This meant users were now receiving meeting requests but crmadmin was also getting a copy.
The next step is to configure Dynamics CRM Email Router to use Impersonation but this requires the "Sent As" permission to be enabled and this requires a call to Microsoft Online Support.