Faxing via the Ring Central website allows a user to select the date and time to send the fax.
Faxes sent by email (e.g. email@example.com) should be "schedulable" in the same way. Perhaps the start date and time can be written into the Subject Line and this will indicate to Ring Central servers when to send the fax out. If the date and time are incorrectly formatted in relation to a prescribed format, just send the fax as normal.
This feature would let mass faxes be scheduled for hours that fax machines are less busy (e.g. overnight)