1. Add a reference to the Microsoft.CrmSdk.Workflow NuGet package.
2. Create a new folder in your Visual Studio solution called CustomWorkflow.
3. Create a new abstract class called BaseCustomWorkflow that inherits from CodeActivity:

public abstract class BaseCustomWorkflow : CodeActivity 

4. Add the following using statements:

using Microsoft.Xrm.Sdk; 
using System.ServiceModel; 
using Microsoft.Xrm.Sdk.Workflow; 
using Packt.Xrm.Extensions.DataAccessLayer; 
using System.Activities; 

5. Add the following protected instance variables:

protected IOrganizationService OrganizationService; 
protected ICustomTracingService CustomTracingService; 
protected DataAccessLayerFactory DataAccessLayerFactory; 
protected IWorkflowContext WorkflowContext; 

6. Add the following abstract method:

public abstract void PostExecute(CodeActivityContext executionContext); 

7. Add the following Execute method:

protected override void Execute(CodeActivityContext
   executionContext) 
{ 
   var serviceFactory = 
     executionContext.GetExtension<IOrganizationServiceFactory>(); 
   var tracingService = 
     executionContext.GetExtension<ITracingService>(); 
   WorkflowContext = 
     executionContext.GetExtension<IWorkflowContext>(); 
   OrganizationService = 
    serviceFactory.CreateOrganizationService(WorkflowContext.UserId); 
    try 
    { 
      using (DataAccessLayerFactory = new 
        DataAccessLayerFactory(OrganizationService, tracingService)) 
      { 
         CustomTracingService =
           DataAccessLayerFactory.GetTracingService(); 

            PostExecute(executionContext); 
       } 
    } 
    catch (FaultException<OrganizationServiceFault> ex) 
    { 
       throw new InvalidPluginExecutionException("An error occurred
         in the UpdateActivities plug-in.", ex); 
    } 
    catch (Exception ex) 
    { 
        CustomTracingService.Trace("FollowupPlugin: {0}",
           ex.ToString()); 
        throw; 
    } 
} 

8. In the same CustomWorkflow folder, create a new public class called UpdateEmailsWorkflowActivity that inherits from BaseCustomWorkflow.
9. Add the following using statements:

using System.Activities; 
using Microsoft.Xrm.Sdk.Workflow; 
using Packt.Xrm.Extensions.BusinessLogic; 

10. Add the following workflow in the argument:

[Input("Account Guid")] 
[Default("00000000-0000-0000-0000-000000000000")] 
public InArgument<string> AccountGuid { get; set; } 

11. Add the following PostExecute method:

public override void PostExecute(CodeActivityContext 
  executionContext) 
{ 
   var input = AccountGuid.Get<string>(executionContext); 
   var accountId = input ==
     Guid.Empty.ToString().Trim('{').Trim('}') ?  
     WorkflowContext.PrimaryEntityId : Guid.Parse(input); 
     CustomTracingService.Trace("Input value {0}", input); 

   var updateEmailLogic = new 
    UpdateEmailLogic(DataAccessLayerFactory.GetEmailDataAccessLayer(), 
     CustomTracingService); 
   updateEmailLogic.UpdateAccountsEmails(accountId); 
}