source: Common/Mail.php

<?php

define('DISPOSITION_INLINE', 'inline');
define('DISPOSITION_ATTACHMENT', 'attachment');

define('CHARSET_ASCII', 'us-ascii');
define('CHARSET_UTF8', 'utf-8');

class Mail
{
  public string $Subject;
  public string $From;
  public array $Recipients;
  public array $Bodies;
  public array $Attachments;
  public string $AgentIdent;
  public string $Organization;
  public string $ReplyTo;
  public array $Headers;
  private array $Priorities;
  private string $Boundary;
  public bool $TestMode;

  function __construct()
  {
    $this->Priorities = array('1 (Highest)', '2 (High)', '3 (Normal)', '4 (Low)', '5 (Lowest)');
    $this->Boundary = md5(date('r', time()));
    $this->AgentIdent = 'PHP/Mail';
    $this->TestMode = false;
    $this->Clear();
  }

  function Clear(): void
  {
    $this->Bodies = array();
    $this->Attachments = array();
    $this->Recipients = array();
    $this->SenderAddress = '';
    $this->SenderName = '';
    $this->Subject = '';
    $this->Organization = '';
    $this->ReplyTo = '';
    $this->Headers = array();
  }

  function AddToCombined(string $Address): void
  {
    $this->Recipients[] = array('Address' => $Address, 'Type' => 'SendCombined');
  }

  function AddTo(string $Address, string $Name): void
  {
    $this->Recipients[] = array('Address' => $Address, 'Name' => $Name, 'Type' => 'Send');
  }

  function AddCc(string $Address, string $Name): void
  {
    $this->Recipients[] = array('Address' => $Address, 'Name' => $Name, 'Type' => 'Copy');
  }

  function AddBcc(string $Address, string $Name): void
  {
    $this->Recipients[] = array('Address' => $Address, 'Name' => $Name, 'Type' => 'HiddenCopy');
  }

  function AddBody(string $Content, string $MimeType = 'text/plain', string $Charset = 'utf-8'): void
  {
    $this->Bodies[] = array('Content' => $Content, 'Type' => strtolower($MimeType),
      'Charset' => strtolower($Charset));
  }

  function Organization(string $org): void
  {
    if (trim($org != '')) $this->xheaders['Organization'] = $org;
  }

  function Priority(int $Priority): bool
  {
    if (!intval($Priority)) return false;

    if (!isset($this->Priorities[$Priority - 1])) return false;

    $this->xheaders['X-Priority'] = $this->Priorities[$Priority - 1];
    return true;
  }

  function AttachFile($FileName, $FileType, $Disposition = DISPOSITION_ATTACHMENT): void
  {
    $this->Attachments[] = array('FileName' => $FileName, 'FileType' => $FileType,
      'Disposition' => $Disposition, 'Type' => 'File');
  }

  function AttachData($FileName, $FileType, $Data, $Disposition = DISPOSITION_ATTACHMENT): void
  {
    $this->Attachments[] = array('FileName' => $FileName, 'FileType' => $FileType,
      'Disposition' => $Disposition, 'Type' => 'Data', 'Data' => $Data);
  }

  function Send(): bool
  {
    if (count($this->Bodies) == 0) throw new Exception(T('Mail message need at least one text body'));

    $Body = $this->BuildAttachment($this->BuildBody());

    $To = '';
    $this->Headers['CC'] = '';
    $this->Headers['BCC'] = '';
    foreach ($this->Recipients as $Index => $Recipient)
    {
      if ($Recipient['Type'] == 'SendCombined')
      {
        if ($Index > 0) $To .= ', ';
        $To .= $Recipient['Address'];
      } else
      if ($Recipient['Type'] == 'Send')
      {
        if ($Index > 0) $To .= ', ';
        $To .= $Recipient['Name'].' <'.$Recipient['Address'].'>';
      } else
      if ($Recipient['Type'] == 'Copy')
      {
        if ($Index > 0) $this->Headers['CC'] .= ', ';
        $this->Headers['CC'] .= $Recipient['Name'].' <'.$To['Address'].'>';
      } else
      if ($Recipient['Type'] == 'HiddenCopy')
      {
        if ($Index > 0) $this->Headers['BCC'] .= ', ';
        $this->Headers['BCC'] .= $Recipient['Name'].' <'.$To['Address'].'>';
      }
    }
    if ($To == '') throw new Exception(T('Mail message need at least one recipient address'));

    $this->Headers['Mime-Version'] = '1.0';

    if ($this->AgentIdent != '') $this->Headers['X-Mailer'] = $this->AgentIdent;
    if ($this->ReplyTo != '') $this->Headers['Reply-To'] = $this->ReplyTo;
    if ($this->From != '')
    {
      $IndexStart = strpos($this->From, '<');
      if ($IndexStart !== false)
      {
        $this->Headers['From'] = '=?utf-8?Q?'.quoted_printable_encode(trim(substr($this->From, 0, $IndexStart))).'?= '.substr($this->From, $IndexStart);
      } else
      {
        $this->Headers['From'] = $this->From;
      }
    }

    $Headers = '';
    foreach ($this->Headers as $Header => $Value)
    {
      if (($Header != 'Subject') and ($Value != '')) $Headers .= $Header.': '.$Value."\n";
    }

    $this->Subject = strtr($this->Subject, "\r\n", '  ');

    if ($this->Subject == '') throw new Exception(T('Mail message missing Subject'));

    if ($this->TestMode)
    {
      echo('to: '.$To.', subject: '.$this->Subject.', body: '.$Body.', headers: '.$Headers);
      $res = true;
    } else
    {
      $res = mail($To, $this->Subject, $Body, $Headers);
    }
    return $res;
  }

  function ValidEmail(string $Address): bool
  {
    if (preg_match(".*<(.+)>", $Address, $regs)) $Address = $regs[1];
    if (preg_match("^[^@  ]+@([a-zA-Z0-9\-]+\.)+([a-zA-Z0-9\-]{2}|net|com|gov|mil|org|edu|int)\$", $Address))
      return true;
      else return false;
  }

  function CheckAdresses(array $Addresses): void
  {
    foreach ($Addresses as $Address)
    {
      if (!$this->ValidEmail($Address))
      {
        throw new Exception(sprintf(T('Mail message invalid address %s'), $Address));
      }
    }
  }

  private function ContentEncoding($Charset): string
  {
    if ($Charset != CHARSET_ASCII) return '8bit';
      else return '7bit';
  }

  private function BuildAttachment($Body): string
  {
    if (count($this->Attachments) > 0)
    {
      $this->Headers['Content-Type'] = "multipart/mixed;\n boundary=\"PHP-mixed-".$this->Boundary."\"";
      $Result = "This is a multi-part message in MIME format.\n".
        "--PHP-mixed-".$this->Boundary."\n";
      $Result .= $Body;

      foreach ($this->Attachments as $Attachment)
      {
        $FileName = $Attachment['FileName'];
        $BaseName = basename($FileName);
        $ContentType = $Attachment['FileType'];
        $Disposition = $Attachment['Disposition'];
        if ($Attachment['Type'] == 'File')
        {
          if (!file_exists($FileName))
            throw new Exception(sprintf(T('Mail message attached file %s can\'t be found'), $FileName));
          $Data = file_get_contents($FileName);
        } else
        if ($Attachment['Type'] == 'Data') $Data = $Attachment['Data'];
          else $Data = '';

        $Result .= "\n".'--PHP-mixed-'.$this->Boundary."\n".
          "Content-Type: ".$ContentType."; name=\"".$BaseName."\"\n".
          "Content-Transfer-Encoding: base64\n".
          "Content-Disposition: ".$Disposition."\n\n";
        $Result .= chunk_split(base64_encode($Data))."\r\n";
      }
    } else $Result = $Body;
    return $Result;
  }

  private function BuildBody(): string
  {
    $Result = '';
    if (count($this->Bodies) > 1)
    {
      $this->Headers['Content-Type'] = 'multipart/alternative; boundary="PHP-alt-'.$this->Boundary.'"';
      $Result .= 'Content-Type: multipart/alternative; boundary="PHP-alt-'.$this->Boundary.'"'.
        "\n\n";
    } else
    {
      $this->Headers['Content-Type'] = $this->Bodies[0]['Type'].'; charset='.$this->Bodies[0]['Charset'];
      $this->Headers['Content-Transfer-Encoding'] = $this->ContentEncoding($this->Bodies[0]['Charset']);
    }

    foreach ($this->Bodies as $Body)
    {
      if (count($this->Bodies) > 1) $Result .= "\n\n".'--PHP-alt-'.$this->Boundary."\n";
      $Result .= 'Content-Type: '.$Body['Type'].'; charset='.$Body['Charset'].
        "\nContent-Transfer-Encoding: ".$this->ContentEncoding($Body['Charset'])."\n\n".$Body['Content']."\n";
    }
    return $Result;
  }
}

/*
// Example
$Mail = new Mail();
$Mail->AddTo('nobody@nodomain', 'Recipient');
$Mail->From = 'No reply <noreply@nodomain>';
$Mail->Subject = 'Test message';
$Mail->AddBody('This is sample message sent by PHP Mail class');
$Mail->AddBody('This is sample <strong>HTML</strong> message sent by <i>PHP Mail class</i>', 'text/html');
$Mail->AttachFile('mailtest.php', 'text/plain');
$Mail->AttachData('DataFile.txt', 'text/plain', 'Sample text');
$Mail->Send();
*/