Post reference: https://powershell.org/forums/topic/powershell-script-to-send-an-email-notification-with-servers-with-disk-space/

powershell-forum-powershell-script-to-send-an-email-notification-with-servers-with-disk-space.ps1

# Script Disk Space
$users = “xxxxxxxx” # List of users to email your report to (separate by comma)
$fromemail = “xxxxxxxxx”
$server = “xxxxxxx” #enter your own SMTP server DNS name / IP address here
$list = "C:\Powershell Script\list.txt" #This accepts the argument you add to your scheduled task for the list of servers. i.e. list.txt
$computers = Get-Content -Path $list #grab the names of the servers/computers to check from the list.txt file.
$mydate = Get-Date

# Set free disk space threshold below in percent (default at 10%)
[decimal]$thresholdspace = 10

#assemble together all of the free disk space data from the list of servers and only include it if the percentage free is below the threshold we set above.
$SelectPropertyList = @(
    '__SERVER'
    'DriveType'
    'VolumeName'
    'Name'
    @{Name = 'Size (Gb)'; Expression = {“{0:n2}” -f ($_.size/1gb)}}
    @{Name = 'FreeSpace (Gb)'; Expression = {“{0:n2}” -f ($_.freespace/1gb)}}
    @{Name = 'PercentFree'; Expression = {“{0:n2}” -f ($_.freespace/$_.size*100)}}
)
$tableFragment = 
    Get-WMIObject -ComputerName $computers Win32_LogicalDisk |
        Select-Object -Property $SelectPropertyList  |
        Where-Object { $_.DriveType -eq 3 -and [decimal]$_.PercentFree -lt [decimal]$thresholdspace } |
        Sort-Object -Property PercentFree |
        ConvertTo-HTML -fragment

# assemble the HTML for our body of the email report.
$HTMLmessage = @”
Disk Space Storage Report
This report was generated because the drive(s) listed below have less than $thresholdspace % free space. Drives above this threshold will not be listed.
body{font: .8em “”Lucida Grande””, Tahoma, Arial, Helvetica, sans-serif;}
ol{margin:0;padding: 0 1.5em;}
table{color:#000000;background:#FFFFFF;border-collapse:collapse;width:647px;border:5px solid #900;}
thead{}
thead th{padding:1em 1em .5em;border-bottom:1px dotted #FFF;font-size:120%;text-align:left;}
thead tr{}
td{padding:.5em 1em;}
tfoot{}
tfoot td{padding-bottom:1.5em;}
tfoot tr{}
#middle{background-color:#900;}
$tableFragment
Generated on $mydate
“@

# Set up a regex search and match to look for any tags in our body. These would only be present if the script above found disks below the threshold of free space.
# We use this regex matching method to determine whether or not we should send the email and report.
$regexsubject = $HTMLmessage
$regex = [regex] '(?im)'

# if there was any row at all, send the email
if ($regex.IsMatch($regexsubject))
{
    $date = (Get-Date).ToString('yyyy/MM/dd')
    Send-MailMessage -From $fromemail -To $users -Subject “SQLServerDiskSpace Report -$date” -BodyAsHTML -body $HTMLmessage -Priority High -SmtpServer $server
}