Hi @BérangèreL ,
Thanks for your reply! Of course also the best wishes to you for 2025 
Let me give you some more details about this:
We have a shared mail address in Outlook “support@domain.com”. This is also connected to HubSpot as channel for the Service Hub. Every team member has also a personal inbox like “john@domain.com”.
When we move over mails to the shared mail address, we copy them from our personal inbox to the inbox of “support@domain.com”. This worked well in the past.
Yesterday, I did a bit of testing.
When I send a test mail to my personal mail address and move it a few minutes after that over to the support inbox, HubSpot gets the mail as a conversation. But this does not work for mails which are older than a few days.
Mails which are forwarded or sent directly to the shared inbox, are recognized by HS without any issues. Sending mails works also fine.
1. We’re on the “Starter” plan, so I think this is not available for us.
2. Just copying/dragging them from one inbox to the other in Outlook.
3. What do you mean exactly? I didn’t do that in my test yesterday or in the past, but it worked fine always.
4. The conversation inbox in HS where new chats and messages from all channels are visible.
5. This happens only to mails which are a few days old (less than a week).
6. It happens for all users.
Hope this helps you to better understand the issue.
Marco