How to change the gridview label's text automatically

If i click the hyperlink buton, the the new webpage will appear and filled with some details for sending mail.

Protected Sub SendMail()
' Gmail Address from where you send the mail
Dim fromAddress = "yourname@gmail.com"
' any address where the email will be sending
Dim toAddress = Email.Text.ToString()
'Password of your gmail address
Const fromPassword As String = "xxxxxxxx"
' Passing the values and make a email formate to display
Dim subject As String = Subject.Text.ToString()
Dim body As String = "From: " + Name.Text & vbLf
body += "Email: " + Email.Text & vbLf
body += "Subject: " + Subject.Text & vbLf
body += "Message: " & vbLf + Message.Text & vbLf
' smtp settings
Dim smtp = New System.Net.Mail.SmtpClient()
If True Then
smtp.Host = "smtp.gmail.com"
smtp.Port = 587
smtp.EnableSsl = True
smtp.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network
smtp.Credentials = New NetworkCredential(fromAddress, fromPassword)
smtp.Timeout = 20000
End If
' Passing values to smtp object
smtp.Send(fromAddress, toAddress, subject, body)
End Sub

This design page coding am using to redirect the page...

<asp:HyperLinkField HeaderText="SEND MAIL" NavigateUrl="mail.aspx"
Text="Send" DataNavigateUrlFields="email"
DataNavigateUrlFormatString="mail.aspx?email={0}" />
<asp:TemplateField HeaderText="MAIL STATUS" >

<asp:Label ID="lab1" runat ="server" Text="Not Sent" >

and using button event on webpage i can goback to the gridview page.