public void Execute(IPluginExecutionContext context)
{
    try
    {
        DynamicEntity entity = null;
        // checks; are we at the right place
        if (context.InputParameters.Properties.Contains("Target") && context.InputParameters.Properties["Target"] is DynamicEntity)
        {   // nearly
            entity = (DynamicEntity)context.InputParameters.Properties["Target"];
            if (entity.Name != EntityName.email.ToString())
            {   // missed!
                return;
            }
        }
        else
        {   // missed
            return;
        }
        // running stage?
        if (context.Stage != (int)MessageProcessingStage.AfterMainOperationOutsideTransaction)
        {   // post please
            throw new InvalidPluginExecutionException("Need to run this plugin post stage");
        }
        // service from context
        ICrmService service = context.CreateCrmService(false);
        // local variables:
        Guid EmailID = Guid.Empty;
        Guid SalesLiteratureID = Guid.Empty;
        CrmNumber attachNo = new CrmNumber(1);
        // Email Guid, attachment number and sales literature guid
        if (entity.Properties.Contains("activityid"))
        {   // update should come here
            Microsoft.Crm.Sdk.Key acid = (Microsoft.Crm.Sdk.Key)entity.Properties["activityid"];
            EmailID = acid.Value;
            // sales literature id
            SalesLiteratureID = this.GetAndClearSalesLiteratureID(service, EmailID);
            // number of attachments
            attachNo = this.GetNextAttachmentNo(service, EmailID);
        }
        else if (context.OutputParameters.Properties.Contains("id"))
        {   // create should come here (annoying, different name!)
            EmailID = new Guid(context.OutputParameters.Properties["id"].ToString());
            // sales literature id
            if (entity.Properties.Contains("new_salesliteratureid"))
            {   // found it
                Microsoft.Crm.Sdk.Lookup lkup = (Microsoft.Crm.Sdk.Lookup)entity.Properties["new_salesliteratureid"];
                SalesLiteratureID = lkup.Value;
            }
            // attachments; assume none!!!
        }
        if (EmailID == Guid.Empty)
        {   // failed
            return;
        }
        if (SalesLiteratureID == Guid.Empty)
        {   // another failure
            return;
        }
        // attach items to the email
        this.AttachSalesLiteratureItemsToEmail(service, SalesLiteratureID, EmailID, ref attachNo);
        // all done
    }
    catch (System.Web.Services.Protocols.SoapException ex)
    {
        throw new InvalidPluginExecutionException(this.GenerateErrorLog("An error occurred in the AttachSalesLiterature plugin: ", ex), ex);
    }
}