If there are 5 scheduled jobs that are already in the queue then MassMailer does not let us create or send mass email. Is there a way you can bypass this limit.
We maintain a queue now so at the time of 5 apex jobs running we save the 6th  request in a queue and run it when the window is open to run the job.i.e we check queue in every 30 minutes and pick the jobs and run until the queue gets empty.
MassMailer Team