#Requires -Version 5.1
<#
    JbTecWiz Support Centre -- generated fix script

    Fault : Outlook cannot set up the account, or connects to the wrong server
    Fix   : Deal with a stale service connection point
    Source: https://jbtecwiz.com/support/win-office-autodiscover

    Run as     : PowerShell on a domain-joined machine
    Expect     : 40 minutes
    Risk       : medium
    Reversible : yes

    WHEN THIS IS THE RIGHT FIX
    The log shows an internal Exchange URL being found, on a network where
    the mailbox has moved to Microsoft 365.

    HOW TO UNDO IT
    Delete the ExcludeScpLookup value to restore the normal lookup order.

    This script walks the fix one step at a time and asks before each
    one. Steps with no command are things you do yourself -- it prints
    those and waits. Run with -DryRun to print without executing.
#>

[CmdletBinding()]
param(
    # Print every step and command without running anything.
    [switch]$DryRun,
    # Do not ask before each step. Read the script first if you use this.
    [switch]$Unattended
)

$ErrorActionPreference = 'Stop'
$script:Failed = 0

function Write-Rule { param([string]$Text)
    Write-Host ''
    Write-Host ('-' * 70) -ForegroundColor DarkGray
    if ($Text) { Write-Host $Text -ForegroundColor Cyan }
}

function Show-Prose { param([string]$Text, [string]$Colour = "Gray")
    if (-not $Text) { return }
    $words = $Text -split "\s+"; $line = "  "
    foreach ($w in $words) {
        if (($line.Length + $w.Length) -gt 74) { Write-Host $line -ForegroundColor $Colour; $line = "  " }
        $line += "$w "
    }
    if ($line.Trim()) { Write-Host $line -ForegroundColor $Colour }
}

function Invoke-Step {
    param(
        [int]$Number, [string]$Do, [string]$Why,
        [scriptblock]$Command, [switch]$Manual, [string]$Shell = "powershell"
    )
    Write-Rule "  Step $Number of 5"
    Show-Prose $Do "White"
    if ($Why) { Write-Host ""; Show-Prose $Why "DarkGray" }

    if ($Manual) {
        Write-Host ''
        Write-Host '  -> Do this yourself, then press Enter to carry on.' -ForegroundColor Yellow
        if (-not $Unattended -and -not $DryRun) { [void](Read-Host) }
        return
    }

    Write-Host ''
    foreach ($l in ($Command.ToString().Trim() -split "`n")) {
        Write-Host ("    " + $l.Trim()) -ForegroundColor Green
    }
    Write-Host ''

    if ($DryRun) { Write-Host "  (dry run -- not executed)" -ForegroundColor DarkGray; return }
    if (-not $Unattended) {
        $a = Read-Host "  Run this step? [Y]es / [S]kip / [Q]uit"
        if ($a -match "^[Qq]") { Write-Host "  Stopped at your request."; exit 0 }
        if ($a -match "^[Ss]") { Write-Host "  Skipped." -ForegroundColor DarkGray; return }
    }
    try { & $Command }
    catch {
        $script:Failed++
        Write-Host ("  Step $Number failed: " + $_.Exception.Message) -ForegroundColor Red
        Show-Prose "The rest of the fix may depend on this. Read the write-up before carrying on." "Red"
        if (-not $Unattended) {
            $c = Read-Host "  Carry on anyway? [y/N]"
            if ($c -notmatch "^[Yy]") { exit 1 }
        }
    }
}

Write-Rule
Write-Host '  Outlook cannot set up the account, or connects to the wrong server' -ForegroundColor White
Write-Host '  Deal with a stale service connection point' -ForegroundColor Cyan
Write-Host ''
Write-Host '  Risk: medium   Reversible   40 minutes'
Write-Rule

if (-not $Unattended -and -not $DryRun) {
    $go = Read-Host '  Ready? [y/N]'
    if ($go -notmatch "^[Yy]") { Write-Host "  Nothing was changed."; exit 0 }
}

Invoke-Step -Number 1 -Do 'List the service connection points published in Active Directory.' -Why 'A domain-joined machine checks AD before it checks DNS, and it trusts what it finds. A decommissioned Exchange server that was never cleanly removed leaves its SCP behind, and every domain-joined client keeps being sent to it.' -Command {
    ([adsisearcher]'(&(objectClass=serviceConnectionPoint)(serviceClassName=ms-Exchange-AutoDiscover-Service))').FindAll() | ForEach-Object { $_.Properties.servicebindinginformation }
}

Invoke-Step -Number 2 -Do 'If the old Exchange server is genuinely gone, the SCP should be removed as part of decommissioning it. That is an Exchange administration task and should be done properly rather than by deleting objects by hand.' -Manual

Invoke-Step -Number 3 -Do 'As an interim measure on affected clients, tell Outlook to skip the SCP lookup.' -Command {
    $k='HKCU:\Software\Microsoft\Office\16.0\Outlook\AutoDiscover'
    New-Item $k -Force | Out-Null
    Set-ItemProperty $k -Name ExcludeScpLookup -Type DWord -Value 1
}

Invoke-Step -Number 4 -Do 'Restart Outlook and run the AutoConfiguration test again to confirm it now moves past that step.' -Manual

Invoke-Step -Number 5 -Do 'Treat the registry value as temporary. It is a client-side workaround for a server-side problem, and it has to be deployed to every machine and every new build until the SCP is actually removed.' -Why 'This is the step that turns a two-week fix into a permanent piece of estate debt if it is skipped. Record it somewhere and remove it once the SCP is gone.' -Manual

Write-Rule "  Confirm it worked"
Show-Prose 'The AutoConfiguration log shows the Microsoft 365 endpoint answering and the account connects correctly.' 'White'

Write-Rule
if ($script:Failed -gt 0) {
    Write-Host ("  Finished with " + $script:Failed + " failed step(s).") -ForegroundColor Yellow
    Show-Prose 'Read the full write-up at https://jbtecwiz.com/support/win-office-autodiscover' 'Yellow'
} else {
    Write-Host '  Finished.' -ForegroundColor Green
}
Write-Host ''
Show-Prose 'To undo: Delete the ExcludeScpLookup value to restore the normal lookup order.' 'DarkGray'
Write-Rule