Active Directory: unable to add multiple email addresses in multi valued property ("targetaddress")

I'm trying to add two different external email addresses for the contacts in the Active Directory. I'm facing the following COMException: A constraint violation occurred.

Here is the DirectoryEntry path= "LDAP://CN=s0010109,OU=RSVContacts,DC=domain,DC=com"

Here is the code :

DirectoryEntry entryAD = new DirectoryEntry("LDAP://CN=s0010109,OU=RSVContacts,DC=domain,DC=com")开发者_如何学Go;    

DirectorySearcher myADSearcher = new DirectorySearcher(entryAD);
                SearchResultCollection resultAD = myADSearcher.FindAll();              

entryAD.Properties["targetaddress"].Value = new string[] { "SMTP:" + "firstemail@abc.com", ""SMTP:" + secondemail@mail.com"};  //;
entryAD.CommitChanges();

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Like what I said in my answer on your previous question, targetAddress is not a multi-value attribute. You cannot do that. You can only have one single value stored in this attribute.