Use email in SharePoint 2010 Sandbox

In SharePoint 2010 Sandbox. In Sandbox Microsoft.SharePoint.Utilitiesis not avaliable. When tried to use System.Net.Mail methods available to us. SmtpClient constructor give me error.
I found another way using SharePoint Designer workflow. You can trigger a workflow to run programmatically and also supply information to the workflow and set the initiation values. Here's the code to start a workflow:

/// /// Method to handle starting the appropriate Workflow as specified by the Site Collection Workflow Name property /// private void StartWorkflow() { SPWorkflowAssociation wfa = SPContext.Current.Web.WorkflowAssociations.GetAssociationByName(this.SiteCollectionWorkflowName, CultureInfo.InvariantCulture); wfa.AssociationData = this.GetWorkflowInitiationData(); SPContext.Current.Site.WorkflowManager.StartWorkflow(null, wfa, this.GetWorkflowInitiationData(), SPWorkflowRunOptions.Asynchronous); } /// /// Method to construct the Workflow Initiation/Association Data /// /// A string containing the XML schema and values necessary for the Association Data private String GetWorkflowInitiationData() { String schema = "http://www.w3.org/2001/XMLSchema\" " + "xmlns:dms=\"http://schemas.microsoft.com/office/2009/documentManagement/types\" " + "xmlns:dfs=\"http://schemas.microsoft.com/office/infopath/2003/dataFormSolution\" " + "xmlns:q=\"http://schemas.microsoft.com/office/infopath/2009/WSSList/queryFields\" " + "xmlns:d=\"http://schemas.microsoft.com/office/infopath/2009/WSSList/dataFields\" " + "xmlns:ma=\"http://schemas.microsoft.com/office/2009/metadata/properties/metaAttributes\" " + "xmlns:pc=\"http://schemas.microsoft.com/office/infopath/2007/PartnerControls\" " + "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\">" + "{0}" + ""; StringBuilder sb = new StringBuilder(); sb.AppendFormat("{0}", this.SendToEmailAddress); sb.AppendFormat("{0}", this._subject.Text); sb.AppendFormat("{0}", this._comments.Text); sb.AppendFormat("{0}", this._email.Text); sb.AppendFormat("{0}", this.AutoResponseSubject); sb.AppendFormat("{0}", this.AutoResponseText); return String.Format(schema, sb.ToString()); }