Dim strEmailAddresses As String = "myaddress1@mail.com, myaddress2@mail.com, INVALID_EMAIL@, myaddress3@mail.com"
Dim emailAddr As String
For Each emailAddr in strEmailAddresses.Split(",")
emailAddr = emailAddr.Trim()
If Not Regex.IsMatch(emailAddr, "([a-zA-Z0-9_\-\.]+)@([a-zA-Z0-9_\-\.]+)\.([a-zA-Z]{2,5})") Then
Console.WriteLine("'{0}' invalid email address", emailAddr)
End If
Next