ADbNewsSender is an easy to install and use php based newsletter script. You can use it to manage multiple newsletters. It is using double opt in and supports MySQL/MariaDB and PostgreSQL. You can also present a web archive to your website's visitor.
Please note that the development has been discontinued. You can still download the software, but you won't receive any support or updates.
This is a phpscript that runs outside Drupal to send your Simplenews
You only need the php file and a form that will initiate it plus a custom unsubscribe page. The script uses simplenews newsletter database tables, users, newsletter categories etc. The only thing you have to do is to disable the simplenews newsletter spool cron from Drupal or choose not to send them form Simplenews/Drupal interafce in order to avoid having both this tool and Drupal cron sending mails.
tellmatic is a php and mysql based newsletter script to create, manage and send personalized newsletters or mass mails. uses wysiwyg and has a form editor. adresses and newsletter are stored in unlimited groups. handle bouncemails and failed adresses
A powerful Newsletter/ Mass Mailer script with built-in ftp client and wysiwyg editor. Ability to set custom attributes for members, queue and send mails at a later time. Easy database backup. Easy integration with the web template.
Create multiple newsletters through the one script, Users can unregister themselves through unregister.php, Admin facility allows you to edit, delete and list the members of each newsletter, Users can choose between HTML and plain text emails.