SharePoint Get all users emal from SPUser objec

        public static string strLDAP = "LDAP://Test.com";



        public static void GetADMails(ref List<string> list, string strLoginName)

        {

            DirectoryEntry newEntry = new DirectoryEntry(strLDAP);

            strLoginName = strLoginName.Substring(strLoginName.LastIndexOf('\\') + 1);

            DirectorySearcher newSearcher = new DirectorySearcher(newEntry, "(&(objectClass=group)(CN=" + strLoginName + "))");

            SearchResult sr = newSearcher.FindOne();

            if (sr != null)

            {

                foreach (string srUser in sr.GetDirectoryEntry().Properties["member"])

                {

                    DirectoryEntry tmpEntry = new DirectoryEntry("LDAP://" + srUser);

                    if (tmpEntry.Properties["objectClass"][1].ToString() == "person")

                    {

                        if (string.IsNullOrEmpty(ConvertNull(tmpEntry.InvokeGet("Mail")).Trim()) || list.Contains(ConvertNull(tmpEntry.InvokeGet("Mail")).Trim()))

                        {

                            continue;

                        }

                        Console.WriteLine(tmpEntry.InvokeGet("Mail"));

                        list.Add(ConvertNull(tmpEntry.InvokeGet("Mail")).Trim());

                    }

                    else

                    {

                        GetADMails(ref list, tmpEntry.InvokeGet("sAMAccountName").ToString());

                    }

                }

            }

            else

            {

                newSearcher = new DirectorySearcher(newEntry, "(&(&(objectCategory=person)(objectClass=user))(cn=" + strLoginName + "))");

                sr = newSearcher.FindOne();

                if (sr != null)

                {

                    object obj = sr.Properties["Mail"][0];

                    if (!(string.IsNullOrEmpty(ConvertNull(obj).Trim()) || list.Contains(ConvertNull(obj).Trim())))

                    {

                        list.Add(ConvertNull(obj).Trim());

                    }

                }

            }

        }



        public static List<string> GetUserMailsByUserField(SPWeb web, object obj)

        {

            List<string> mailarr = new List<string>();

            SPGroup group = null;

            if (obj == null)

            {

                return mailarr;

            }

            try

            {

                SPFieldUserValueCollection approversCollection;

                web.AllowUnsafeUpdates = true;

                approversCollection = (SPFieldUserValueCollection)obj;

                foreach (SPFieldUserValue spFieldUserValue in approversCollection)

                {

                    if (spFieldUserValue.User == null)

                    {

                        //sharepoitn group 

                        try

                        {

                            group = web.SiteGroups[spFieldUserValue.LookupValue];

                            SPUserCollection users = group.Users;

                            foreach (SPUser user in users)

                            {

                                if (user.ID == group.Owner.ID)

                                {

                                    continue;

                                }

                                if (string.IsNullOrEmpty(ConvertNull(user.Email)))

                                {

                                    continue;

                                }

                                if (mailarr.Contains(ConvertNull(user.Email).Trim()))

                                {

                                    continue;

                                }

                                mailarr.Add(ConvertNull(user.Email).Trim());

                            }

                        }

                        catch { }

                    }

                    else

                    {

                        //sharepoint user or ad group

                        try

                        {

                            GetADMails(ref mailarr, web.AllUsers.GetByID(spFieldUserValue.LookupId).LoginName);

                        }

                        catch { }

                    }

                }

            }

            catch (Exception ex)

            {

                Console.WriteLine(ex.Message);

            }

            return mailarr;



        }

List<string> maillist= GetUserMailsByUserField(web, item["Reader"]);