SparkPost was a dedicated A transactional email is the automated message a WordPress site sends in response to a single user action – a password reset, an order confirmation, a form receipt – addressed to the user who triggered it. Read full reference → service founded in 2011 as the cloud version of Message Systems’ Momentum MTA. It built a reputation for high-volume email infrastructure and a generous free tier (100,000 emails/month). MessageBird acquired SparkPost in 2022; MessageBird then rebranded to Bird in 2024. The standalone SparkPost product has been absorbed into Bird’s enterprise CRM and messaging platform.
For WordPress sites evaluating email relay options in 2026: SparkPost is no longer a practical choice. The self-service signup is gone, pricing is enterprise-only (contact sales), and the official WordPress plugin was closed in March 2025 due to a security issue. Existing SparkPost API credentials continue to work, but new WordPress sites should choose a service that is actively maintaining WordPress tooling.
SMTP settings (legacy)
The SparkPost SMTP endpoint remains documented and functional for existing accounts:
| Setting | Value |
|---|---|
| Host | smtp.sparkpostmail.com (US) or smtp.eu.sparkpostmail.com (EU) |
| Port | 587 (STARTTLS) or 2525 (alternate) |
| Encryption | STARTTLS required |
| Authentication | AUTH LOGIN |
| Username | SMTP_Injection (literal string, not your email) |
| Password | API key with "Send via SMTP" permission |
The username is always the literal string SMTP_Injection. The API key serves as the password.
Acquisition timeline
| Date | Event |
|---|---|
| 2011 | SparkPost launched (cloud offering of Message Systems’ Momentum MTA) |
| 2016 | Free tier: 100K emails/month (made it popular with WordPress developers) |
| 2022 | Acquired by MessageBird |
| 2024 | MessageBird rebrands to Bird; SparkPost brand retired from product pages |
| March 2025 | Official WordPress plugin closed (reason: security issue) |
WordPress integration (current state)
The official SparkPost WordPress plugin (last updated August 2023, tested up to WP 6.3.8) was permanently closed on the WordPress.org repository in March 2025 due to a security issue. It is no longer available for download.
For existing SparkPost users who still have valid API credentials, connection via a general mailer plugin remains possible:
| Plugin | Method | Notes |
|---|---|---|
| WP Mail SMTP | "Other SMTP" | Use SMTP settings above |
| FluentSMTP | "Other SMTP" | Manual SMTP configuration |
| Post SMTP | SMTP | Manual credentials |
No mailer plugin offers a dedicated SparkPost/Bird integration with OAuth or API-level features. Connection is SMTP-only via generic credentials.
What SparkPost offered (historical context)
At its peak, SparkPost was a strong transactional email service with capabilities that matched or exceeded Mailgun and Postmark:
- Delivery webhooks (bounce, delivery, open, click, spam complaint)
- Dedicated IP addresses
- Inbound email parsing
- Template engine with Handlebars syntax
- Real-time delivery analytics
- Email validation API
- Subaccount isolation
These features technically remain available to existing accounts via the SparkPost API. Whether Bird will maintain them indefinitely is unclear; the brand is being consolidated into Bird’s broader enterprise platform.
Verdict
SparkPost is no longer available as a self-service product. The self-service signup is gone, the WordPress plugin was closed in March 2025, and the parent company (Bird) has repositioned toward enterprise CRM with sales-only pricing. There is no onboarding path for a WordPress site owner who wants to sign up today.
Existing SparkPost users with working API credentials can continue using the SMTP endpoint via a general mailer plugin. There is no immediate urgency to migrate if email is flowing, but the long-term trajectory is clear: Bird is not investing in WordPress-focused tooling or self-service email relay.
Migration alternatives:
- SMTP2GO for the closest equivalent (reliable relay, simple setup, free tier).
- Postmark for deliverability-focused transactional email.
- Mailgun for developers who want API-first infrastructure (same general category as SparkPost).
For the broader setup that places Bird inside the WordPress email stack, see the WordPress email setup guide.