How to turn off the lead assignment email notification ??

In my case,We don't have any Assignment rules ,lead owner is changed through apex trigger ,We don't want users to receive these Lead Assignment notifications .

Thanks in Advance.

Attribution to: Keepcalmncode

Possible Suggestion/Solution #1

This is similar to another that I answered, you might find it useful: Case Assignment Notification Suppression

SF Documentation on the EmailHeader option: http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_methods_system_database_dmloptions.htm#emailheader

The relevant part:

//THIS DMLOPTION SEEMS TO BE IGNORED IN BEFORE UPDATE TRIGGERS
Database.DMLOptions dlo = new Database.DMLOptions();
dlo.EmailHeader.triggerAutoResponseEmail = false;
dlo.EmailHeader.triggerUserEmail = false;
dlo.EmailHeader.triggerOtherEmail = false;

database.update(casesList,dlo);

Attribution to: Jon Hazan

Possible Suggestion/Solution #2

There is some workaround would be to create a Queue, assign the user to that - and then uncheck the "email members of queue" in the Queue setup. Then assign those leads to that Queue rather than the user directly. By using this method, you can turnoff email notification for specific user as well.

Attribution to: Vishal Pandey
This content is remixed from stackoverflow or stackexchange. Please visit https://salesforce.stackexchange.com/questions/1686