Retarus Transactional Email vs Twilio SendGrid

Retarus Transactional Email sends high volumes of transactional messages from business applications through Retarus Enterprise Cloud. It offers REST API and SMTP interfaces, with JSON and SMTP/MIME formats, and direct connections to SAP, Microsoft, Salesforce, and ServiceNow. Retarus reports a delivery rate of 98% or higher and guaranteed processing capacity of 100,000 emails per hour; its Email API page separately states capacity of up to 10 million per hour. Administrators can use the myEAS web portal for dashboards, real-time monitoring, reporting, and configuration. The Email API can locate outbound messages by time, message ID, sender, or recipient and provides status information for the past 45 days. Security features include SPF, DKIM, DMARC, enforced TLS, antivirus multiscan, encrypted attachments, and message signing. Retarus processes data in self-operated centers in Germany, Switzerland, the United States, and Asia. The service is paid, with pricing on request. Its free trial costs nothing for 30 days, permits up to 5,000 emails, caps processing at 200 emails per hour, and excludes load testing.

Twilio SendGrid Email API sends email through a cloud-based delivery service, so customers do not need to maintain their own email servers. Messages can be sent through its RESTful Web API, SMTP relay, or SMTP API, with open-source client libraries for C#, Go, Java, Node.js, PHP, Python, and Ruby. Tools include dynamic templates, an Email Validation API, deliverability insights, and email testing. The Email Activity API, Event Webhook, and Activity dashboard track deliveries, opens, clicks, bounces, unsubscribes, and spam reports. Security features listed include SPF, DKIM, DMARC, TLS encryption, and API keys that can be limited or revoked. Twilio states a 99% deliverability rate. A 60-day free trial is listed at free, with limits of 100 emails per day and 100 contacts. Pay as you go is free; Essentials starts at $19.95 a month and Pro at $89.95 a month. Each email to one recipient uses a credit, even if deferred or sent to spam. Twilio says SendGrid does not natively support HIPAA-compliant data transmission.