How do I delete multiple messages from all employee mailboxes for specific sender in Exchange?

Question

Multimedia department have one user twasul use to send an email of advertisement with different subjects since 3 years till now, Exchange server storage fired up storage increasing.

How do I delete multiple messages from all employee mailboxes from all employee for specific sender twasul?

I tried:

1. Done: New-ManagementRoleAssignment -Role "Mailbox Import Export" -User "administrator"
2. Done: New-ManagementRoleAssignment -Role "Mailbox Search" -User "administrator"
3. Done: Search-Mailbox -Identity 'twasul' -EstimateResultOnly
4. I Am Confused: Search-Mailbox -Identity "twasul" -TargetMailbox (????) -TargetFolder "\inbox" -LogOnly -LogLevel Full
5. I feel like if I did this step it will clear twasul mailbox instead of all employee: Search-Mailbox -Identity "twasul" -DeleteContent

Although, I don't have a same (-SearchQuery 'Subject:"Your bank statement"') so what to do!

foreach ($mailbox in (get-mailbox)) {Search-Mailbox -id $mailbox -DeleteContent -Force}(not work !!)

I guess I have to put all employee on one group but this does not work:

`Search-Mailbox -identity "employee_group" -SearchQuery 'Received&;amp;amp;amp;lt;01/01/2018 .. 12/30/2018 ' -SearchDumpster:$false –deletecontent`

And this does not work either:

`Search-Mailbox -SearchQuery 'received="year" AND received>30/12/2018'`