Send-MailMessage Bug

config.xml

<?xml version="1.0"?>
<settings>
	<mail>
		<from>from@gmail.com</from>
    		<to>to@gmail.com</to>
		<subject>Test</subject>
    		<smtp>smtp.gmail.com</smtp>
    		<port>587</port>
    		<user>from@gmail.com</user>
    		<pass>frompassword</pass>
  	</mail>
</settings>

dockerfile

FROM microsoft/powershell
RUN mkdir /smmbug
ADD . /smmbug
ENTRYPOINT ["pwsh", "/smmbug/job.ps1"]

job.ps1

Set-Location (Split-Path -Parent $MyInvocation.MyCommand.Path)
[xml]$cfg = Get-Content "config.xml"

$m = $cfg.settings.mail
$sp = ConvertTo-SecureString $m.pass -AsPlainText -Force
$c = New-Object pscredential ($m.user, $sp)
$files = ([string[]]((gci)|%{$_.name}))

$msg = @{ 
    Port = $m.port
    Credential = $c
    From = $m.from
    To = $m.to
    Subject = $m.subject
    Attachments = $files
    SmtpServer = $m.smtp
    UseSsl = $true
}

"---sending the following files:"
$files
Send-MailMessage @msg
"---sent"