how to take application control back from application_error - gmail

Question

I got an old application that is using aspnet membership controls changepassword and createuserwizard etc. These send emails in the end, via gmail, after sending the email successfully, I get an application_error
The SMTP server requires a secure connection or the client was not authenticated...
The requirement is I can go back to the normal flow of application and ignore this error.
Note that the email is being sent successfully to the client. There is no exception within the procedure/catch.
Protected Sub ChangePwd_SendingMail(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.MailMessageEventArgs) Handles ChangePwd.SendingMail
Dim obj As SecurePassword = New SecurePassword()
Select Case ConfigurationSettings.AppSettings("WhichSMTP")
Case "gmail"
Try
obj.SendViaGmail(e.Message.Subject, e.Message.Body, e.Message.To.ToString())
Catch ex As Exception
Response.Write("Error sending email via gmail smtp: " & ex.Message)
End Try
End Select
End Sub
SecurePassword.vb
Public Function SendViaGmail(subject As String, body As String, recipients As String)
Dim fromEmail As String = ConfigurationSettings.AppSettings("ContactEmail")
Dim smtpClient As SmtpClient = New SmtpClient("smtp.gmail.com") With {
.Port = 587,
.DeliveryMethod = SmtpDeliveryMethod.Network,
.Credentials = New NetworkCredential(fromEmail, "apppasswordgeneratedviagoogle"),
.EnableSsl = True
}
Dim mailMessage As MailMessage = New MailMessage With {
.From = New MailAddress(fromEmail),
.Subject = subject,
.Body = body,
.IsBodyHtml = True
}
mailMessage.[To].Add(recipients)
If smtpClient IsNot Nothing Then
smtpClient.Send(mailMessage)
End If
End Function
I got the above code from here
few things to note,
I am running this code from my development machine (IISExpress).
previously there was no code written under
Case "gmail"
Update:
I have tried catching it in page_error, it actually comes here but it shows me an empty page now instead of successtemplate from changepassword control
Private Sub Page_Error(sender As Object, e As EventArgs) Handles Me.Error
Dim exc As Exception = Server.GetLastError()
' Handle specific exception.
If exc.GetType = GetType(SmtpException) Then
ChangePwd.SuccessTemplate.InstantiateIn(ChangePassword)
'ChangePwd.ChangePasswordTemplateContainer.Visible = False
End If
' Clear the error from the server.
Server.ClearError()
End Sub