How to update a custom field status when the email(from send an email functionality) has been send

Question

I have created a custom filed in Orders that is a picklist field. On default is pending.

How can I automatically update this field to send when I use the send an email functionality through the activity history?

Answer 1

You will need to write a trigger on the Task object.

Then you can perform your picklist value change if a Task object is created where the WhatId field is an Order object and the Subject field begins with 'Email:'.

trigger TaskTrigger on Task (after insert) {
    List<Order> ordersToUpdate = new List<Order>();

    for(Task t : Trigger.new) {
        if(t.WhatId.getSObjectType() == Order.sObjectType 
            && t.Subject.startsWith('Email:')) {
                ordersToUpdate.add(new Order(Id = t.WhatId, My_Picklist_Field__c = 'New Value'));
        }
    }

    update ordersToUpdate;
}