• Mailing list segmentation: Organization of your newsletter subscribers in niche-targeted groups of interest.
• Spam filter preview: Test to verify if major Internet providers will treat your email newsletter as spam.
• Customizable API: Integration of the newsletter distribution service with your business applications or content management system.
• Personalization: Automatically address your newsletter subscribers using their first names or company names.
• Analytics: Reports and statistics about the performance of your email newsletter (subscribes, unsubscribes, opened emails, etc.)
• Manual Mailing List Import: Upload of your subscribers by hand (instead of using an automatic procedure) to have greater control over your mailing lists and avoid spam.
• Custom Sign-up Form: Management of the data fields to include in the embeddable sign-up form for your newsletter.
• Price: Cost of the email newsletter distribution service.
And this list is not complete in itself as there many other viable options are available in the market.