There are a couple of options you can deselect within the activity setup to stop reports being attached to emails.
1) To stop the attachment of the summary report (i.e the report that tells you the status of each device), uncheck the 'Attach additional report with sortable columns' option in the activity setup E-mail tab.
2) To prevent the Diff reports (ConfigChanges.zip) from being attached, uncheck the 'Attach reports to e-mail' option in the activity setup Options tab.
Hope this helps,
Thanks a lot Steve, your solution have helped me.
I guess i was just blind