What it does
UniOne delivers transactional and marketing emails through web and SMTP APIs, with templates, event notifications and reports. A new account can test mail to its own verified domains. The wider StartUp trial includes 6,000 monthly emails for four months and requires a payment card before converting to a paid subscription.
UniOne's initial Free account is a constrained test stage: it can send up to 100 emails per day only to domains added and verified in that account. Sending to other recipient domains requires a subscription, including the StartUp trial.
In Settings / Sending domains, use the plus button to add your domain. Add its displayed DNS records at your domain provider, then select Verify. Once the status checks are green, send a message through SMTP or the Web API. The API also supports event notifications, templates and unsubscribe management. To activate the wider trial, open Billing and subscribe to StartUp 6K with a credit or debit card. It includes 6,000 monthly emails and 100 address validations for four months after signup, then becomes a paid monthly plan. Additional messages and validations incur overage charges. Use Modify subscription in Billing to change the allowance.
Strengths
- A restricted verified-domain stage supports initial integration checks
- Web and SMTP APIs are accompanied by templates and event notifications
Watch out for
- The initial Free test account cannot send to arbitrary recipient domains
- The four-month trial becomes paid and extra usage can incur charges
Best for
- Product teams staging an email integration before opening delivery to customer domains
Sources
- Transactional Email Service | API Email System - UniOne (Oct 25, 2026)
- Email API plans pricing | UniOne (Oct 27, 2026)
- Getting Started With UniOne (Oct 27, 2026)