告知他人未收到信件或回复，可以采用以下几种英语表达方式：

1. 若已发送邮件，却未收到回复，可以这样表达："If you have already sent me an email, I'm afraid it seems to have gotten lost in my inbox. I apologize for any inconvenience, but could you please send it to me again?" 表示抱歉并请求重发。

2. 追踪邮件状态时，可以这样表述："I hope this message finds you well. I just wanted to follow up on the email I sent last week to make sure you received it. If you haven't, could you please let me know so I can resend it?" 表示关心并确认邮件接收情况。

3. 确认邮件是否收到，可以这么问："I wanted to check in and make sure that you had received my previous email. If you haven't, please let me know and I'll be happy to send it again." 提供再次发送的选项。

4. 确认邮件接收，可以这样确认："I just wanted to confirm that you received the email I sent last week. If not, please let me know and I will resend it as soon as possible." 明确询问接收情况并提供重发。

所有这些表达方式都应包含询问和礼貌，同时为对方提供重新发送邮件的机会，确保信息能及时传递。