To disable email delivery reports:
1) Open the ActiveSMS Console
2) Go to the Email tab
3) Click the ‘Email Formats…’ button
4) Select the ‘SMS Message Sent Report’ and unselect ‘Generate This Message’
5) Select the ‘SMS Message Send Failure Report’ and unselect ‘Generate This Message’
6) Select the ‘SMS Message Delivery Report’ and unselect ‘Generate This Message’
7) Select the ‘SMS Message Non-Delivery Report’ and unselect ‘Generate This Message’
8) Click ‘OK’
9) Click ‘Apply’
NOTE: After making the changes you will probably have some reports queued up.
To clear the queue you can either:
1) Purge the Incoming Queue (this will also purge incoming SMS messages)
2) Configure the SMTP settings to clear the queue