search email from mailbox, and force hard delete

Create a content search

Then use PS to force a delete

Import-Module ExchangeOnlineManagement

Connect-IPPSSession -UserPrincipalName <UPN> [-ConnectionUri <URL>] [-AzureADAuthorizationEndpointUri <URL>] [-PSSessionOption $ProxyOptions]

New-ComplianceSearchAction -SearchName “Remove Phishing Message” -Purge -PurgeType SoftDelete

New-ComplianceSearchAction -SearchName “Remove Phishing Message” -Purge -PurgeType HardDelete

Get-ComplianceSearchAction

Get-ComplianceSearchAction -Identity “Case 1234_Preview” | Format-List

Get-ComplianceSearch | FL name,items,size,jobprogress,status