SharePoint Access Requests Settings

A part of the PS commands are not yet integrated into CSOM

This is why is developed that script for example:

<#
Source:
 - https://sharepoint.stackexchange.com/questions/219634/sp-online-powershell-web-requestaccessemail-is-not-returning-any-value
 - https://sharepoint.stackexchange.com/questions/241415/csom-property-for-access-request-group
 - https://msdn.microsoft.com/en-us/library/office/microsoft.sharepoint.client.web.aspx
 - https://techcommunity.microsoft.com/t5/SharePoint-Developer/Changing-the-quot-Allow-members-to-share-quot-SharePoint-site/td-p/18562
#>

[string]$MyRootWebURL = "https://tenant.sharepoint.com/sites/YourSiteCollection"
[string]$SiteOwnerEmailAdress = ""
[boolean]$ChangeRequestAccessEmail = $true

[string]$username = "admin@tenant.onmicrosoft.com"
[string]$PwdTXTPath = "C:\SECUREDPWD\ExportedPWD-$($username).txt"

$secureStringPwd = ConvertTo-SecureString -string (Get-Content $PwdTXTPath)
$creds = New-Object System.Management.Automation.PSCredential $username, $secureStringPwd

function Load-DLLandAssemblies
{
	[string]$defaultDLLPath = ""

	# Load assemblies to PowerShell session 

	$defaultDLLPath = "C:\Program Files\SharePoint Online Management Shell\Microsoft.Online.SharePoint.PowerShell\Microsoft.SharePoint.Client.dll"
	[System.Reflection.Assembly]::LoadFile($defaultDLLPath)

	$defaultDLLPath = "C:\Program Files\SharePoint Online Management Shell\Microsoft.Online.SharePoint.PowerShell\Microsoft.SharePoint.Client.Runtime.dll"
	[System.Reflection.Assembly]::LoadFile($defaultDLLPath)

	$defaultDLLPath = "C:\Program Files\SharePoint Online Management Shell\Microsoft.Online.SharePoint.PowerShell\Microsoft.Online.SharePoint.Client.Tenant.dll"
	[System.Reflection.Assembly]::LoadFile($defaultDLLPath)
}

Function Invoke-LoadMethod() {
param(
   [Microsoft.SharePoint.Client.ClientObject]$Object = $(throw "Please provide a Client Object"),
   [string]$PropertyName
) 
   $ctx = $Object.Context
   $load = [Microsoft.SharePoint.Client.ClientContext].GetMethod("Load") 
   $type = $Object.GetType()
   $clientLoad = $load.MakeGenericMethod($type) 


   $Parameter = [System.Linq.Expressions.Expression]::Parameter(($type), $type.Name)
   $Expression = [System.Linq.Expressions.Expression]::Lambda(
            [System.Linq.Expressions.Expression]::Convert(
                [System.Linq.Expressions.Expression]::PropertyOrField($Parameter,$PropertyName),
                [System.Object]
            ),
            $($Parameter)
   )
   $ExpressionArray = [System.Array]::CreateInstance($Expression.GetType(), 1)
   $ExpressionArray.SetValue($Expression, 0)
   $clientLoad.Invoke($ctx,@($Object,$ExpressionArray))
}

function Get-SPOSubWebs
{
	Param( 
        [Microsoft.SharePoint.Client.ClientContext]$Context, 
        [Microsoft.SharePoint.Client.Web]$RootWeb 
    ) 
	
	$Webs = $RootWeb.Webs
	$Context.Load($Webs)
	$Context.ExecuteQuery()
	ForEach ($sWeb in $Webs)
	{
		Write-host " -------------------------------------------------------- "
		Write-host "       -->> SubSite:", $sWeb.URL -ForegroundColor green
		Invoke-LoadMethod -Object $sWeb -PropertyName "HasUniqueRoleAssignments"
		$context.ExecuteQuery()
		Write-Host "       -->> Has Unique Permissions:", $sWeb.HasUniqueRoleAssignments

		if($sWeb.HasUniqueRoleAssignments)
		{

			Invoke-LoadMethod -Object $sWeb -PropertyName "RequestAccessEmail"
			Invoke-LoadMethod -Object $sWeb -PropertyName "MembersCanShare"
			Invoke-LoadMethod -Object $sWeb -PropertyName "AssociatedMemberGroup"
			Invoke-LoadMethod -Object $sWeb -PropertyName "AssociatedOwnerGroup"
			$context.ExecuteQuery()
			Write-Host "            -->> Request Access Email Before change:", $sWeb.RequestAccessEmail, " - Member Can Share:", $sWeb.MembersCanShare, "- AssociatedMemberGroup.AllowMembersEditMembership: " $sWeb.AssociatedMemberGroup.AllowMembersEditMembership -ForegroundColor Red
			Write-Host "            -->> AssociatedOwnerGroup Name:", $sWeb.AssociatedOwnerGroup.Title   -ForegroundColor Yellow
			
			if(($ChangeRequestAccessEmail) -and ($sWeb.RequestAccessEmail -ne $SiteOwnerEmailAdress))
			{
				Write-Host "      ===->> Request Access Email to change"
				$sWeb.RequestAccessEmail = $SiteOwnerEmailAdress
				$sWeb.Update()
				$context.ExecuteQuery()
				Invoke-LoadMethod -Object $sWeb -PropertyName "RequestAccessEmail"
				$context.ExecuteQuery()
				Write-Host "   -->> Request Access Email After change:", $sWeb.RequestAccessEmail
			}

		}
		Get-SPOSubWebs -Context $Context -RootWeb $sWeb
	} 
}


cls
Write-Host " ---------------------------------------------- "
Load-DLLandAssemblies
Write-Host " ---------------------------------------------- "

	$Myctx = New-Object Microsoft.SharePoint.Client.ClientContext($MyRootWebURL)

	$Myctx.Credentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($creds.UserName,$creds.Password)
	$Myctx.RequestTimeout = 1000000 # milliseconds
	$MyspoRootweb = $Myctx.Web
	$Myctx.Load($MyspoRootweb)
	$Myctx.ExecuteQuery()

Write-Host " "
Write-Host " ---------------------------------------------------------"
Write-Host "  >>>> # Server Version:" $Myctx.ServerVersion " # <<<<<<" -ForegroundColor Green 
Write-Host " ---------------------------------------------------------"
Write-Host " "

Write-host " -------------------------------------------------------- "
Write-host "   -->> RootSite:", $MyspoRootweb.URL -ForegroundColor green

Invoke-LoadMethod -Object $MyspoRootweb -PropertyName "RequestAccessEmail"
Invoke-LoadMethod -Object $MyspoRootweb -PropertyName "MembersCanShare"
Invoke-LoadMethod -Object $MyspoRootweb -PropertyName "AssociatedMemberGroup"
Invoke-LoadMethod -Object $MyspoRootweb -PropertyName "AssociatedOwnerGroup"
$Myctx.ExecuteQuery()

Write-Host "   -->> Request Access Email Before change:", $MyspoRootweb.RequestAccessEmail -ForegroundColor Red
Write-Host "       ==> Member Can Share:", $MyspoRootweb.MembersCanShare
Write-Host "       ==> AssociatedMemberGroup Name:", $MyspoRootweb.AssociatedMemberGroup.Title ,"- AssociatedMemberGroup.AllowMembersEditMembership: " $MyspoRootweb.AssociatedMemberGroup.AllowMembersEditMembership  -ForegroundColor Yellow
Write-Host "       ==> AssociatedOwnerGroup Name:", $MyspoRootweb.AssociatedOwnerGroup.Title   -ForegroundColor Yellow

if(($ChangeRequestAccessEmail) -and ($MyspoRootweb.RequestAccessEmail -ne $SiteOwnerEmailAdress))
{
	Write-Host "   ===->> Request Access Email to change"
	$MyspoRootweb.RequestAccessEmail = $SiteOwnerEmailAdress
	$MyspoRootweb.Update()
	$Myctx.ExecuteQuery()
	Invoke-LoadMethod -Object $MyspoRootweb -PropertyName "RequestAccessEmail"
	$Myctx.ExecuteQuery()
	Write-Host "   -->> Request Access Email After change:", $MyspoRootweb.RequestAccessEmail
}

Get-SPOSubWebs -Context $Myctx -RootWeb $MyspoRootweb

That will give you the solution to manage that value at any level of the site collection.

To remove the access request, you just have to let the value "" into the variable $SiteOwnerEmailAdress

If you want to set it to someone, set the email address.

You can adapt that code as you need.

Fab