The tool is designed to mailbox enable the ActiveDirectory mail-enabled object or from a mail-enabled contact. Once the mailbox enabling process is completed, the database quota is left enabled.
Is there a way to disable database quota once the object is mailbox-enabled or while mailbox-enabling?
Default behavior.
Below is the part of the CMDLET the tool runs by default:
DEBUG: PSCMDLET: Set-MailBox -Identity CN=User Name,OU=Exchange Objects,DC=domain,DC=com -DomainController DC1.domain.com -Confirm False -EmailAddressPolicyEnabled False
Above CMDLET does not have the switch that leaves the mailbox enabled object's database quota disabled.
WORKAROUND
Once the mailbox enabled process is completed, disable to the database quota manually.