症狀
使用 Set-ExchangeServer -InternetWebProxy Cmdlet 在 Microsoft Exchange Server 2019 中設定 Proxy 伺服器之後，新式附件功能無法運作。 如果您傳送的電子郵件訊息在 Outlook 網頁版 (OWA) 中包含新式附件，則會記錄以下事件：
From: Microsoft Outlook <microsoftexchange329e71ec88ae4615bbc36ab6ce41109e@contoso.com>
To: <the user who just sent out a modern attachment>
Subject: Your recipients couldn't be given access to the file <file name>
Body: The location where the file is stored isn't available.
The message was sent, but recipients might not be able to access the attachment.
Try opening the file <filename> and giving others access to it from its current location.
解決方式
若要修正此問題，請安裝下列累積更新：
適用於 Exchange Server 2019 的累積更新 14 或適用於 Exchange Server 2019 的較新累積更新