how to check mutiple domain with mutiple email address

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ASP.NET

Hello,

i have one field name client domain name
where i storing mutiple domain name example:gmail.com,yahoo.co.in

and i have mutiple email address like :
belge.sadhana@gmail.com,belge.sadhana@yahoo.co.in

how to check the domain valid for that email ids.

my code:

 if (ds.Tables[0].Rows[0]["DomainName"].ToString() != "")
                    {
                       
                        DomainAddress = ds.Tables[0].Rows[0]["DomainName"].ToString();

                        DEmailAdress = DomainAddress.Split(',');
                        
                        
                      
                            MutipleEmailID = txtBCCEmail.Text + "," + txtCCEmail.Text + "," + lblToEmailId.Text;

                            string[] spilitemailids = MutipleEmailID.Split(',');

                            foreach (string id in spilitemailids)
                            {

                                foreach (string s in DEmailAdress)
                                {
                                   address = new MailAddress(id);

                                    if (!id.Contains("@insyncanalytics.com"))
                                    {
                                        if (!address.Host.Equals(s, StringComparison.OrdinalIgnoreCase))
                                        {
                                            if (id.Contains(s))
                                            {
                                          

                                            }
                                            else
                                            {
                                                //bad domain
                                                InvalidDomainEmailAddress.Add(address);

                                            }
                                    
                                        }
                                    }
                             }

                        }

                    }

                }
            }
        }
        catch (Exception ex)
        {

        }
        finally
        {
            if (conn.State == ConnectionState.Open)
            {
                conn.Close();
            }
 
        }
return InvalidDomainEmailAddress;

my problem is when i loop two emailids added in arraylist i got belge.sadhana@gmail.com and belge.sadhana@yahoo.co.in.
but this two domain address is exit in the database.
but domain address exit in the database then this email id should not add in arraylist

but how i can get the answer

plz help me