Exchange 365 and in-place eDiscovery

Question

I created dozens of in-place eDiscovery search in powershell for the users who have left the company, but we need to retain their mailboxes for legal compliance reasons. The powershells looked like this:
New-MailboxSearch -name "User1" -SourceMailboxes [email protected] -ExcludeDuplicateMessages $true -InPlaceHoldEnabled $true -ItemHoldPeriod 255
And when I go into the EAC> Compliance Mgmt> in-place eDiscovery, I can see all of them but their status says "Status: Search Not Started."  So I used the EAC to edit one, and check if I missed something, but everything from the PS script
is correct, and when I clicked Save, again without actually changing anything, the search did start at that point! I looked at a few other cmdlets, and I found the start-mailboxsearch. So I issued:
start-MailboxSearch -Identity "User1"
But that comes back with "Unable to execute the task. Reason: TargetMailbox is required for copying messages returned by the search." So why am I able to use the EAC eDiscovery portion without having to specify TargetMailbox, but when I use Powershell
I do have specify it?

Answer 1

Instead of an in-place hold, one workaround may be to use set-mailbox cmdlet with parameters LitigationHoldEnabled and LitigationHoldDuration .
This *may* have a  couple advantages:
1. LitigationHold is the entire account and is binary (it's either on or off),
2. A New-MailboxSearch on that mailbox can still be done if needed (and assuming the account is on hold, see above),
3. A MailboxSearch for IPH/eDiscovery can be removed if no longer needed without affecting the account on hold.
Hope that helps and gives you a creative spark.