send email in VBA

Dear Expert,

I found one strange problem, when I am doing sent email to my client in VBA,
VBA code at .send (see attach code)  will come one dialog box to warn and ask me whether to continue to
send the message that might be virus" and then I manually  press "yes to finish
the rest  the VBA code. The Client doesn't recevie any email until
I re-open outlook software and quit it. THe client can receive the email right away. Why ?

and the other question, how to avoid the message warning dialog window, and I try
to set Application.DisplayAlerts = False but it is not working at all

Please advise for those two question and view my attach VBA code for email send

Function sendmail()
Set app = CreateObject("outlook.application")
Set itm = app.CreateItem(0)
Application.DisplayAlerts = False

With itm
.Subject = "dail report"
.To = "duncanuk9@hotmail.com.hk"
.Body = "daily last report"
'.Display
.Send  """"""""""""""""""Warning dialog window will came out to ask me whether to continue ? 
End With
Set app = Nothing
Set itm = Nothing

End Function

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