Disabling AD account from a list one account per day

I am trying to disable the AD account based on the input.TXT file one AD account per day, followed by an email when successful.

Input.TXT content:

User1.Name
Person1.Name
Person2.name
user2.Name
...
UserX.name
PersonX.Name

If the scheduled task is restarted, the script should ideally continue to the next active AD account in the list.

This script will be run using the Scheduled task at 12:01 AM every midnight.

So far, here's what I've produced:

$users = Get-Content "C:\userlist.txt"
$emailFrom = "your@email.com"
$emailTo = "recipient@email.com"
$smtpServer = "smtp.yourserver.com"

foreach ($user in $users) {
    try {
        Disable-ADAccount $user
        Send-MailMessage -From $emailFrom -To $emailTo -Subject "User Account Disabled" -Body "$user's account has been disabled." -SmtpServer $smtpServer
    } catch {
        Send-MailMessage -From $emailFrom -To $emailTo -Subject "Error Disabling User Account" -Body "An error occurred while disabling $user's account: $_" -SmtpServer $smtpServer
    }
    Start-Sleep -Seconds 86400
}

I would personally let the task finish daily removing one user at a time from the file. A Queue makes sense to me but could be also done with a List.

try {
    [System.Collections.Generic.Queue[string]] $users = Get-Content 'C:\userlist.txt'

    # is there something to process in the file?
    if(-not $users.Count) {
        # if not, the just exit this task
        return
    }
    # get the first user in queue
    $first = $users.Dequeue()

    $sendMailMessageSplat = @{
        From       = 'your@email.com'
        To         = 'recipient@email.com'
        Subject    = 'User Account Disabled'
        Body       = "$first's account has been disabled."
        SmtpServer = 'smtp.yourserver.com'
    }

    $user = Get-ADUser $first
    # if the user is enabled
    if($user.Enabled) {
        # disable and send email
        $user | Disable-ADAccount
        Send-MailMessage @sendMailMessageSplat
    }
    # if they were already disabled, nothing to do
    # save the file
    Set-Content 'C:\userlist.txt' -Value $users.ToArray()
}
catch [Microsoft.ActiveDirectory.Management.ADIdentityNotFoundException] {
    # if this user doesn't exist, then just save the file.
    # could send email here too if needed
    Set-Content 'C:\userlist.txt' -Value $users.ToArray()
}
catch {
    # if something failed send the email. file is not saved in this case
    # as this use will need to be re-processed
    $sendMailMessageSplat['Subject'] = 'Error Disabling User Account'
    $sendMailMessageSplat['Body'] = "An error occurred while disabling $first's account: $_"
    Send-MailMessage @sendMailMessageSplat
}

I think you can do this by reading the file (skipping empty lines), taking the top line as the user to disable and then save the rest of the lines back to the file to process the next day.

$inputFile = 'C:\userlist.txt'
# read the file, skipping empty or whitespace-only lines
$content = Get-Content -Path $inputFile | Where-Object { $_ -match '\S' }

# create a splatting Hashtable
$mailParams = @{
    From       = 'your@email.com'
    To         = 'recipient@email.com'
    SmtpServer = 'smtp.yourserver.com'
}

# are there any lines left?
if (@($content).Count -eq 0) {
    $mailParams['Subject'] = "File '$inputFile' is empty"
    $mailParams['Body']    = "No users to disable in file '$inputFile'"
}
else {
    # get the first line
    $user = $content[0]
    # and save all further lines back to the file to process the next day
    $content | Select-Object -Skip 1 | Set-Content -Path $inputFile -Force

    try {
        Disable-ADAccount -Identity $user -ErrorAction Stop
        $mailParams['Subject'] = 'User Account Disabled'
        $mailParams['Body']    = "$user's account has been disabled."
    }
    catch {
        $mailParams['Subject'] = 'Error Disabling User Account'
        $mailParams['Body']    = "An error occurred while disabling $user's account: $($_.Exception.Message)"
    }
}
# send out the email
Send-MailMessage @mailParams