C# List Unions with blank values
<p>I have 2 Lists containing email addresses.  I am joining them using a list union to get the final email list, however at times, either of the lists could be empty.  What's happening is when a list is empty, it's adding it to the final list as "" after the union, which is causing the email .Send() to crash on the empty email address.  How can I tell the union to ignore empty values?  Here's what I have</p>

<pre><code>List&lt;string&gt; _RecordOwnerEmailList = new List&lt;string&gt;();

List&lt;string&gt; _SubmissionEmailList = new List&lt;string&gt;();
List&lt;string&gt; _EmailList = new List&lt;string&gt;();

string _RecordOwnerEmails = String.Empty;
string _SubmissionEmails = String.Empty;

if (dsRecordOwner.Tables[0].Rows.Count &gt; 0 &amp;&amp; !String.IsNullOrEmpty(dsRecordOwner.Tables[0].Rows[0]["UpdateEmail"].ToString()))
    _RecordOwnerEmails = dsRecordOwner.Tables[0].Rows[0]["UpdateEmail"].ToString().Replace(" ", "");

if (this.ID &gt; 0)
    _RecordOwnerEmailList = new List&lt;string&gt;(_RecordOwnerEmails.Replace(" ", "").Split(';').ToList());

if (dsEmails.Tables[0].Rows.Count &gt; 0 &amp;&amp; !String.IsNullOrEmpty(dsEmails.Tables[0].Rows[0]["Emails"].ToString()))
    _SubmissionEmails = dsEmails.Tables[0].Rows[0]["emails"].ToString().Replace(" ", "");

_SubmissionEmailList = new List&lt;string&gt;(_SubmissionEmails.Replace(" ", "").Split(';').ToList());

_EmailList = _RecordOwnerEmailList.Union(_SubmissionEmailList).ToList();

string[] emails = _EmailList.ToArray();

foreach (string emailAddress in emails)
{ 
    //send email
}
</code></pre>
