Call excel macro on receiving outlook mail

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VBA

So I have made this macro in excel that checks outlook inbox and downloads attachments from mails coming from certain user. For now, I run the macro manually at a specific time. But I want the macro to get fired when that particular mail enters the mailbox. I mostly work with excel macros and want it to operate from excel side only as much as possible. Moreover, the mailbox will be someone else's so I do not want to do much there.

What I have tried:

Public Sub db_upload()

    'download file from outlook
    Dim ns As Outlook.Namespace
    Dim inbox As Outlook.MAPIFolder
    Dim mail As Object
    Dim attachmnt As Outlook.Attachment
    Dim fname As String
    Dim docPath As String
    Dim i As Integer
    Dim wsh As Object
    Dim fs As Object
    cnt = 0

    Set ns = GetNamespace("MAPI")
    Set inbox = ns.GetDefaultFolder(olFolderInbox)
    maildt = Format(Now, "dd-mm-yyyy")

    For Each mail In inbox.Items
        On Error Resume Next
        namesender = mail.SenderName
        mailsub = mail.Subject
        maildate = Format(mail.ReceivedTime, "dd-mm-yyyy")

        If InStr(mail.Subject, "something") > 0 And Format(mail.ReceivedTime, "dd-mm-yyyy") = maildt Then
            For Each attachmnt In mail.Attachments
                fname = attachmnt.Filename
                attachmnt.SaveAsFile "path" & attachmnt.Filename
                cnt = cnt + 1
            Next attachmnt
        End If
    Next mail

    Set inbox = Nothing
    Set ns = Nothing
    Set fs = Nothing
    Set wsh = Nothing
End Sub