Hi @Karnali Dhanani ,
According to your description, you have changed the email id of the User, created and deleted a distribution list with same legacy name, and then changed the user email address back, is it right?
If so, I have tested on my environment(change the usermailbox "@...com" to "@...com", create a distribution list "@...com", delete the distribution list, change the usermailbox to "@...com"), but all messages could dispaly normally when I login this account in my Outlook with the new email address on new machine. In my opinion, the messages shouldn't be affected if we only changed the user address, so considering your steps may have any differences with mine.
I log in in outlook and I saw there nothing inside
For this situation, in order to confirm if your messages have been removed, please first log in your web mail to check.
If you also couldn't find anything in your web mail, I'm afraid these messages may have been removed from your server, please understand that Outlook is a client that syncing with your server, and we may not be able to recover it in Outlook without any data files.
Besides, if you could find your messages in web mail, considering the issue may be related to your client, it's suggested to check your account setting and switch to "Online mode" to check if the issue has any difference(File>Account Settings>Account Settings>choose your account>uncheck the cached exchange mode).
Hope that would be helpful to you.
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