Form is sent to back after function runs - vb.net

Question

I've got the following section of code:
Public Sub SendTestEmail()
Try
Dim Mail As New MailMessage
Mail.Subject = "Test email"
Mail.To.Add(smtpTXTsendto.Text)
Mail.From = New MailAddress(smtpTXTusername.Text)
Mail.Body = "This is a test message"
Dim SMTP As New SmtpClient(smtpTXTserver.Text)
If smtpCHECKssl.Checked = True Then
SMTP.EnableSsl = True
Else
SMTP.EnableSsl = False
End If
SMTP.Credentials = New System.Net.NetworkCredential(smtpTXTusername.Text, smtpTXTpassword.Text)
SMTP.Port = smtpTXTport.Text
SMTP.Send(Mail)
MessageBox.Show("A test email has been sent." & Environment.NewLine & Environment.NewLine & "To: " & smtpTXTsendto.Text & Environment.NewLine & "From: " & smtpTXTusername.Text & "." & Environment.NewLine & Environment.NewLine & "If you did not recieve an email, please check your settings and try again.", "Test Email")
Catch ex1 As Exception
MessageBox.Show(ex1.Message)
Return
End Try
End Sub
The Sub SendTestEmail is called inside of a Background worker.
The odd issue I'm having, as that when a MessageBox appears, and I click OK the form gets sent to the back of the screen, behind all applications ...
I've tried adding a Me.focus, but it gives me issues about Cross Tread violations.
Any ideas why this is happening?
Background Worker Code:
Private Sub BGWSendTestEmail_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BGWSendTestEmail.DoWork
SendTestEmail()
End Sub
Private Sub BGWSendTestEmail_RunWorkerCompleted(ByVal sender As System.Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BGWSendTestEmail.RunWorkerCompleted
If (e.Cancelled) Then
MsgBox("Something went wrong!")
Else
GroupBoxTesting.Visible = False
Me.Enabled = True
End If
End Sub
Private Sub SMTPButtonTest_Click_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles SMTPButtonTest.Click
GroupBoxTesting.Visible = True
Me.Enabled = False
BGWSendTestEmail.RunWorkerAsync()
End Sub

Answer 1

Change BGWSendTestEmail_RunWorkerCompleted to something like this and remove exception handling from SendTestEmail
Me.Enabled = True ' Always enable form first after completed
If e.Error Is Nothing Then
If Not e.Cancelled Then
MessageBox.Show("A test email has been sent." _
& Environment.NewLine _
& Environment.NewLine _
& "To: " & smtpTXTsendto.Text _
& Environment.NewLine _
& "From: " & smtpTXTusername.Text _
& "." & Environment.NewLine _
& Environment.NewLine _
& "If you did not recieve an email, please check your settings and try again.", _
"Test Email")
GroupBoxTesting.Visible = False 'Maybe put this also into start of method?
Else
MsgBox("Something went wrong!")
End If
Else
MessageBox.Show("Email sending failed. Exception: " & e.Error.Message)
End If
If you debug this program your debugger will attach exceptions in do_work method, but if you run it without debugger then exceptions are handled at completed method.