Smtp2go

SMTP2GO is a straightforward transactional email service at a competitive price point — SMTP relay for apps that already use SMTP libraries, plus a REST API for direct integration. For agents: the REST API sends single emails and retrieves delivery statistics. Free tier (1,000/month) covers development and small-scale production. No complex template system — suitable for simple notification and transactional email workflows. Confidence is docs-derived.

REST API at api.smtp2go.com/v3. POST /email/send sends an email ({api_key, to: ["recipient <email>"], sender: "sender@domain.com", subject, text_body, html_body, attachments}). POST /email/send with template_id sends using saved template. GET /stats/email_bounces retrieves bounce list. GET /stats/email_unsubscribes retrieves unsubscribes. GET /activity retrieves send activity log. SMTP relay: configure outgoing SMTP server to mail.smtp2go.com:2525 (or 587/465) with SMTP2GO credentials. No batch send API — use loop for multiple recipients (rate limit aware).

API key auth: api_key in request body (not header). Keys from SMTP2GO Dashboard → Settings → API Keys. HTTPS enforced. No OAuth2. SMTP credentials: use SMTP2GO account username + password for SMTP relay auth.

Standard HTTP status codes with JSON responses ({status: "success"|"error", data: {...}}). Simple flat error messages. Rate limiting: depends on plan. Bounce handling: soft and hard bounces tracked — hard bounces auto-suppressed. Unsubscribes: tracked for campaign emails. SMTP2GO uptime at status.smtp2go.com. Free tier: 1,000 emails/month — straightforward hard limit.

apidoc.smtp2go.com covers REST API reference. smtp2go.com/docs covers SMTP relay setup and API guide. Getting started: create SMTP2GO account (free), get API key — first email in under 5 minutes. Simple REST interface — no official SDK needed. Community via SMTP2GO support. Minimal but adequate documentation for a focused email delivery service.