Optimize your email deliverability at scale on our custom MTA (with a 99.999% uptime, you can count on us!) Maximize deliverability with SPF records, custom DKIM, and suppression management. Send personalized content with real-time design editing, point-to-click HTML rendering, and conditional testing. Most affordable email blast sender service. SMTP2GO means rock solid reliability. Sending mass emails is important if you're marketing a product or service to your list. All straight from your inbox. ... If you did, you need to adjust the email storage in your cPanel and attempt to do Our mass email service can break Gmail's sending limits.