Forcing Outlook Fonts via Intune

Im familiar with PowerShell but I have no experience at all with this.

I'd contact the creator itself, he is familiar with this, maybe there is an easy fix.

My AI says powershell can handle those hex numbers. 

I'll leave the suggested code from my AI but I highly recommend to test it only in DEV Environments aswell as contact your linkedin contact.

function Convert-HexCsvToByteArray {
    param([string]$Csv)
    $Csv -split ',' |
        Where-Object { $_ -ne '' } |
        ForEach-Object { [Convert]::ToByte(($_ -replace '\s',''), 16) }
}

$bytesSimple          = Convert-HexCsvToByteArray $ValueSimple
$bytesComposeComplex  = Convert-HexCsvToByteArray $ValueComposeComplex
$bytesReplyComplex    = Convert-HexCsvToByteArray $ValueReplyComplex
$bytesTextComplex     = Convert-HexCsvToByteArray $ValueTextComplex

$registryPath = 'HKCU:\SOFTWARE\Microsoft\Office\16.0\Common\mailsettings'
$Name1Simple = "ComposeFontSimple"
$Name1Complex = "ComposeFontComplex"
$Name2Simple = "ReplyFontSimple"
$Name2Complex = "ReplyFontComplex"
$Name3Simple = "TextFontSimple"
$Name3Complex = "TextFontComplex"

if (-not (Test-Path $registryPath)) {
    New-Item -Path $registryPath -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name NewTheme -Value '' -PropertyType String -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name $Name1Simple  -Value $bytesSimple         -PropertyType Binary -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name $Name2Simple  -Value $bytesSimple         -PropertyType Binary -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name $Name3Simple  -Value $bytesSimple         -PropertyType Binary -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name $Name1Complex -Value $bytesComposeComplex -PropertyType Binary -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name $Name2Complex -Value $bytesReplyComplex   -PropertyType Binary -Force | Out-Null
    New-ItemProperty -Path $registryPath -Name $Name3Complex -Value $bytesTextComplex    -PropertyType Binary -Force | Out-Null
}
else {
    Set-ItemProperty -Path $registryPath -Name NewTheme -Value $null
    New-ItemProperty -Path $registryPath -Name ThemeFont -Value 2 -PropertyType DWord -Force | Out-Null
    Set-ItemProperty -Path $registryPath -Name $Name1Simple  -Value $bytesSimple
    Set-ItemProperty -Path $registryPath -Name $Name2Simple  -Value $bytesSimple
    Set-ItemProperty -Path $registryPath -Name $Name3Simple  -Value $bytesSimple
    Set-ItemProperty -Path $registryPath -Name $Name1Complex -Value $bytesComposeComplex
    Set-ItemProperty -Path $registryPath -Name $Name2Complex -Value $bytesReplyComplex
    Set-ItemProperty -Path $registryPath -Name $Name3Complex -Value $bytesTextComplex
}