will setting the msexchangemailboxguid to null cause issues

[Eric Fehn]

we are migrating our mail using BitTitan. the exchange server is not hybrid. Before the migration you have to set the msexchangemailboxguid to $NULL or you wont be able to provision a mailbox. After the mail is migrated they want to convert the exchange server to hybrid. Will setting the msexchangemailbox guid to NULL cause an issue when I convert the exchange server to a hybrid server?  is it safe to restore the msexchangemailboxguid at any time after the migration?

[#2]

That's something that you need to clear with BitTitan support, I suppose they want to do remote moves thus need matching GUIDs, but I'm not sure I understand the need to null the GUID first.

[#3]

I have tried to discuss the issue with BitTitan support, however they will only answer questions directly pertaining how their software operates.
To answer the other question you need to set the MsExchangeMailboxGuid to NULL to get any third party software to work when doing a mailbox migration.