Increase the size allowed for email size on the SMTP server, from what you state it is clearly an email server size limit for the email being sent.
Unable to send E-Mail. Please check SMTP server settings and E-Mail addresses.
This started 3 months ago i can go into reporting and reduce the number of machines reporting by a 1/3 and the reports will be sent. I currently track 739 leased devices. But i have seen files sizes at are 33mb and larger for the e-mail report. Any suggestions on how to get the reporting to work again.