blastengine

What blastengine is

blastengine (ブラストエンジン) is a Japanese email delivery service for developers: an API and an SMTP relay that let a company's own systems send transactional mail and bulk sends without running a mail server. It is provided by RAKUS Light Cloud Co., Ltd., which the site describes as part of the RAKUS Group, a listed company known for business services such as Rakuraku Seisan and Rakuraku Meisai. The headline promises fast delivery and a deliverability rate above 99% ("99％以上の高いメール到達率を実現"), and the company's blog calls blastengine an email service for engineers, chosen by companies that cannot afford to have system mail stop: sign-up notices, password resets and purchase confirmations.

blastengine is the developer-side sibling of blastmail, the same group's newsletter tool, and the site says blastengine's delivery platform was built with blastmail's technology. The blog frames the difference plainly: blastmail is aimed at email marketing beginners, while blastengine was developed for technical users who need more complex and flexible customization.

Two ways to send

blastengine offers two delivery methods, API and SMTP relay, and the site says a customer can use both on one account without any option fee. The FAQ also confirms that using the API carries no extra charge.

The email delivery API lets in-house core systems, or systems on cloud platforms such as AWS, GCP and Azure, send email and fetch delivery results. The site describes it as a RESTful API designed for developers that fits into applications and websites in many environments. Because blastengine builds each message from the API request, the customer needs no mail server of its own. The documentation covers immediate and bulk sends and log retrieval, SDKs are published for languages such as Python and PHP, and a Getting Started guide sits beside the API reference.

The SMTP relay suits systems that already send mail. Most mail clients and servers support SMTP, so the site says moving an existing sending setup across is easy, and no coding is needed: the relay starts working once the server details and credentials are entered. The site says the relay lets a company send large volumes without being judged as spam, and SMTP AUTH stops it being abused as an open relay.

Webhooks notify a URL of your choice when events such as delivery errors occur, and the news section records that webhook notifications were added for SMTP relay sends as well. The same news section announces an MCP server that lets an AI agent send email and analyze results through natural-language conversation.

Delivery work blastengine takes over

The pitch to engineers is that blastengine runs the parts of email that eat their time. Its feature list names:

• sending logic per carrier and ISP, adapted to Japanese mobile carriers' own receiving policies and optimized for each destination domain
• automatic bounce handling that identifies the cause and then resends or stops delivery
• IP reputation management, with delivery monitoring, high-quality IPs and blocklist handling
• a delivery log that keeps sends and bounce information for a set period, searchable and viewable
• merge codes for personalized content in bulk sends
• IP address restrictions on access to the management console
• SPF, DKIM and DMARC support, with help setting them up
• TLS encryption of message content in transit

The site says blastengine meets Gmail's sender guidelines, so mail to Gmail addresses avoids blocking and the spam folder, and one of the ten problems it lists solving is spoofing, through BIMI. When something goes wrong, the log shows when, to which address and for what reason an error occurred, so a resend can happen quickly. The blog cites a delivery speed of 15 million emails per hour and deliverability to Japanese addresses above 99%, and the home page adds that delivery abroad is stable as well.

Plans and prices

There is no setup fee, and the site places its prices among the lowest in the industry. Business plans are priced by monthly volume, each with a per-email overage rate:

• 10,000 emails: 3,000 yen a month, 0.60 yen per extra email
• 30,000 emails: 8,000 yen, 0.50 yen
• 50,000 emails: 12,000 yen, 0.40 yen
• 100,000 emails: 16,000 yen, 0.40 yen
• 200,000 emails: 30,000 yen, 0.30 yen
• 300,000 emails: 40,000 yen, 0.25 yen
• 500,000 emails: 50,000 yen, 0.225 yen
• 1,000,000 emails: 80,000 yen, 0.20 yen
• 1,500,000 emails: 100,000 yen, 0.20 yen
• 2,000,000 emails: 120,000 yen, 0.20 yen

Above 2,000,000 emails a month, pricing is by quote through a short form. Paid options cover a larger attachment size, extra users with roles that limit which features each person can use, a relaxed API rate limit, more recipients per SMTP connection, and a custom bulk delivery API for sending many different transactional messages at once.

The free trial needs only an email address and a password, with no credit card, and the account opens the same day. There is no automatic move to a paid plan and no time limit, though the FAQ says accounts that go unused or appear to send abusively may be suspended. The trial is a verification account limited to 5 addresses per send and 10,000 emails a month. Real sends to customers belong on a business plan, which is chosen in the console, reviewed after application, and can start the same day at the earliest.

Security, data and support

The site says blastengine runs in a domestic Japanese data center that is managed around the clock, 24 hours a day and 365 days a year, with access recorded and monitored and logs retained. RAKUS Light Cloud holds the Privacy Mark and ISMS certification, and the site states that it has had no serious information leak. Customers who want service-level details on information security and the handling of personal data are invited to contact the company.

Support is in Japanese, by phone and email, and covers consultation before adoption, operating support from specialist staff and technical support. During the trial, questions are answered by phone, email and online meeting; the phone line, 03-6862-7337, is open 10:00 to 17:00 on weekdays. A sales partner program lets systems integrators, marketing support firms and web production companies refer or resell blastengine and blastmail, and the FAQ confirms that an agency can hold the contract and provide the service to its own clients. A published integration lets Rakuraku Meisai use blastengine as its external mail server for sending billing document emails.

Customer stories

Three case studies on the home page show typical use. Nippon TV Wands sends payment and donation confirmation emails for its 24-hour TV cashless donation site through blastengine after Gmail began filtering them as spam; it cites easy DKIM setup and says the spam-folder problem improved. IBM Japan uses blastengine for mass alerts from its disaster information system for local governments, where mail to Japanese carriers had been throttled; it chose the service because it needs no database sync with the customer's data, and reports that the throttling problems stopped. Yomiuri Shimbun moved its breaking news emails off self-managed servers, citing lower cost than running its own servers and the ability to point the one-click unsubscribe header link at its own system.

Who it suits

blastengine fits Japanese companies whose applications send transactional mail or sudden bulk alerts to Japanese recipients, including mobile carrier addresses, and who want the delivery tuning, bounce handling and IP reputation work done for them. Developers get a REST API, SDKs, webhooks and an MCP server; teams with an existing mail server can switch to the SMTP relay without writing code. The monthly plans start low, and the free trial account lets a team test the API with no card and no deadline.

It is a sending engine rather than a newsletter tool. The blog steers marketers who want an editor and templates toward blastmail and presents blastengine as the choice for system integration, and all support is in Japanese.