Imports System.Data.OleDb
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim connetionString As String
        Dim connection As OleDbConnection
        Dim oledbAdapter As OleDbDataAdapter
        Dim oledbCmdBuilder As OleDbCommandBuilder
        Dim ds As New DataSet
        Dim i As Integer
        Dim sql As String
        connetionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Your mdb filename;"
        connection = New OleDbConnection(connetionString)
        sql = "select * from tblUsers"
        Try
            connection.Open()
            oledbAdapter = New OleDbDataAdapter(sql, connection)
            oledbCmdBuilder = New OleDbCommandBuilder(oledbAdapter)
            oledbAdapter.Fill(ds)
            For i = 0 To ds.Tables(0).Rows.Count - 1
                ds.Tables(0).Rows(i).Item(2) = "neweamil@email.com"
            Next
            oledbAdapter.Update(ds.Tables(0))
            connection.Close()
            MsgBox("Email address updates !")
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Sub
End Class