Set new users manager via ServiceNow

Hi,

We have integrated ARS with SNOW to post SOAP messages to ARS for the provisioning of users.

Does anyone have any ideas on how we can set the new user's manager details in AD by passing their managers email address on the SNOW provisioning form? 

My understanding is that the manager is set via the managers CN attribute however SNOW is not aware of this and will only have access to the managers email address, how can we integrate this as part of the workflow? 

TIA.