List < string > lSubject; string strSubject; string strTest = ""; string strCheck = "QQ"; if (pEmailHeaders.ContainsKey("subject")) { lSubject = pEmailHeaders["subject"]; strSubject = lSubject[0]; if (strSubject.Length >= 2) { strTest = strSubject.Substring(0, 2); } if (strTest == strCheck) { lSubject[0] = strSubject.Substring(strCheck.Length, strSubject.Length - strCheck.Length); pEmailHeaders["subject"] = lSubject; return true; } } return false;