Applescript to fix emails with hidden attachments

set newFileName to (path to temporary items folder from user domain as string) ¬
        & (random number from 10000 to 99999) ¬
        & ".eml"
tell application "Mail"
        set selectedMails to the selection
        if the length of selectedMails is greater than 0 then
                repeat with theMessage in selectedMails
                        set newSource to my replaceText("Content-Type: multipart/related;", "Content-Type: multipart/mixed;", source of theMessage)
                        set newFile to open for access newFileName with write permission
                        write newSource to newFile starting at 0
                        close access newFile
                        open newFileName
                end repeat
                tell application "Finder" to delete file newFileName
        else
                display alert "Selezionare uno o più messaggi e riprovare"
        end if
end tell

on replaceText(find, replace, someText)
        set prevTIDs to text item delimiters of AppleScript
        set text item delimiters of AppleScript to find
        set someText to text items of someText
        set text item delimiters of AppleScript to replace
        set someText to "" & someText
        set text item delimiters of AppleScript to prevTIDs
        return someText
end replaceText