SPWeb web = SPContext.Current.Web;
bool result = SPUtility.SendEmail(web, true, true, "addressTo@sgart.local", "Mail inviata da SharePoint", "<b>ok</b> funziona");
oppure per specificare il mittente (from) e la priorità
System.Collections.Specialized.StringDictionary headers = new System.Collections.Specialized.StringDictionary();
//mittente
headers.Add("from", "addressFrom@sgart.local");

headers.Add("to", "addressTo@sgart.local");
headers.Add("cc", "addressCc@sgart.local");
headers.Add("bcc", "addressBcc@sgart.local"));
headers.Add("subject", "Mail inviata da SharePoint");
headers.Add("content-type", "text/html");
//priorità
headers.Add("X-Priority", "1 (Highest)");
headers.Add("X-MSMail-Priority", "High");
headers.Add("Importance", "High");

SPUtility.SendEmail(web, headers, "<b>ok</b> funziona", false);