Mail Them Pro
Mail Them Pro is designed for newsletter mailings and mailing lists management. It has own high performance built-in SMTP server, so you don't need to use your ISP's SMTP server. But if you want you still can use your ISP to send emails with an incredible speed. Personalize and merge individual information into any message allows you to create really personal e-mails. You can merge up to 10 different custom fields.