Retarus Transactional Email vs turboSMTP

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.

turboSMTP is a cloud SMTP service for sending email messages and newsletters, with statistical analysis for individual and aggregate messages. Its SMTP API supports transactional messages such as login confirmations, welcome messages, and receipts from a website or app. The dashboard tracks clicks and opens in real time, while listed tools manage bounces, spam, and unsubscribes. Deliverability features include smart routing, custom tracking domains, and email validation before campaigns. An email marketing tool can design, send, and track campaigns using turboSMTP delivery infrastructure. The service lists SMTP relay, email templates, delivery event webhooks, and a dedicated IP option; inbound email is not supported. It offers a free plan allowing 200 emails per day for the first six months. Basic costs €14.95 a month for 15,000 emails per month; Pro costs €79.95 a month for the same send limit and up to 100 subaccounts. Other listed plans sell email credits, which expire one year after purchase. Platforms include Android, API, iOS, and web. The maker advertises 24/7 multilingual support by phone, chat, and email.