You can retrieve information on indexes, such as the primary keys, by querying the Indexes collection.

Retrieving Primary Key Information

To retrieve this schema collection, call the GetSchema method of the EmailConnection class. You can restrict the results by table name. The following example retrieves the primary key of the IMAP table [INBOX].

C#

String connectionString = "Port=993;Server=outlook.office365.com;Password=password;User=user;Protocol=IMAP;SMTP Port=587;SMTP Server=smtp.office365.com;";

using (EmailConnection conn = new EmailConnection(connectionString)) {
  conn.Open();
  DataTable databaseSchema = conn.GetSchema("Indexes", new string[] {"[INBOX]"});
  foreach (DataRow row in databaseSchema.Rows) {
    Console.WriteLine(row["INDEX_NAME"]);
    Console.WriteLine(row["PRIMARY"]);
  }
}

VB.NET

Dim connectionString As String = "Port=993;Server=outlook.office365.com;Password=password;User=user;Protocol=IMAP;SMTP Port=587;SMTP Server=smtp.office365.com;"

Using conn As New EmailConnection(connectionString)
  conn.Open()
  Dim databaseSchema As DataTable = conn.GetSchema("Indexes",  New String() {"[INBOX]"})
  For Each row As DataRow In databaseSchema.Rows
    Console.WriteLine(row("INDEX_NAME"))
    Console.WriteLine(row("PRIMARY"))
  Next
End Using

Columns Returned

The Indexes schema collection contains the following columns: