1. Open Exchange Online PowerShell:
   

1. First, connect to Exchange Online PowerShell using the following commands:
   

   #$UserCredential = Get-Credential

   #Connect-ExchangeOnline -UserPrincipalName <admin_user_email> -ShowProgress $true
   

2. Enable Archiving for All Users:
   

1. Use the following command to enable archiving for all mailboxes:
   

   #Get-Mailbox -Filter {ArchiveStatus -Eq "None"} | Enable-Mailbox -Archive

2. This will enable the archive mailbox for all users who do not currently have it enabled.  
   
   
3. Check Archiving Status:
   
1.  To verify which users have archiving enabled, run the following command:
   #Get-Mailbox | Select-Object DisplayName,ArchiveStatus  
2. This will display a list of users and their archiving status (Active means archiving is enabled).
   
   
4. Close PowerShell Session:
   
1. Once you're done, close the PowerShell session using:
   #Disconnect-ExchangeOnline

Manually enable Online Archive via Microsoft Exchange admin center

1. Open the Exchange Admin Center (EAC)
   
1. In the left-hand menu, scroll down to Admin centers.
2. Click on Exchange to open the Exchange Admin Center.
   
   
2. Go to Recipients
   
1. In the EAC, in the left navigation pane, click on Recipients.
   
2. Under Recipients, click Mailboxes
   
3. List of all the mailboxes in your organization.
   
   
3. Select the Mailboxes
   
1. Single User: To enable archiving for a single user, click on the user’s mailbox to select it.
   
   
4. Enable Archive Mailbox
1. After selecting the mailbox or mailboxes, navigate to Others option in the right-hand pane, scroll down to the In-Place Archive section.
2. Click on Enable next to In-Place Archive
   
   
5. Verify Archive Activation