https://community.hubspot.com/t5/Tickets-Conversations/Undeliverable-messages/m-p/513540#M2867 <P>Hi&nbsp;<a href="https://community.hubspot.com/t5/user/viewprofilepage/user-id/248582">@TienThinker0902</a>&nbsp;, thank you for your post.</P> <P>&nbsp;</P> <P>I see that you attempted to send emails to those "Unknown Visitor" and it failed. When a contact appears as "Unknown Visitor", it usually means this person's contact record no longer exists in your HubSpot account. Could you please verify this?</P> <P>&nbsp;</P> <P>And if there are actually their contact records, could you please share the URL so that I can have a closer look?&nbsp;</P> <P>&nbsp;</P> <P>Thanks!</P> Thu, 21 Oct 2021 06:33:59 GMT natsumimori 2021-10-21T06:33:59Z