Transactional emails

Quickly send transactional emails via SMTP or API. We have a free account, so you can test it.

Send emails using SMTP

Add Mailrelay’s server details into your application and start sending immediately.

Our SMTP server stands out for its high performance. We employ multiple proprietary technologies to automatically improve your delivery rate.

Bounces, spam reports and unsubscribe requests are managed automatically.


Use the SMTP API to easily send transactional emails from your website, CRM, or web apps to your subscribers.

API documentation

$curl = curl_init();

curl_setopt_array($curl, [
    CURLOPT_URL => "https://youraccount/api/v1/send_emails", CURLOPT_RETURNTRANSFER => true, CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => [ "x-auth-token: YOUR_API_KEY", "content-type: application/json" ],
    CURLOPT_POSTFIELDS => json_encode([
        "from" => [ "email" => "[email protected]", "name" => "Sender name" ],
        "to" => [ ["email" => "[email protected]", "name" => "Rcpt name"] ],
        "subject" => "My subject",
        "html_part" => "<p>Hello!</p>"

$response = curl_exec($curl);


Email effectiveness reports

Measure email metrics regularly to improve your email marketing performance and ROI.

Access all key reports – like how many people open and click your emails, how well they reach inboxes, delivery success and issues, and any spam complaints received.

Immediate Benefits


Improved deliverability

Transactional emails tend to have higher deliverability rates than promotional emails, as they are sent in response to a specific user action and are thus expected by the recipient.


Customer Engagement

Transactional emails, such as order confirmations or shipping notifications, keep customers informed and engaged throughout their interaction with a company or service.

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Increase trust and security

By sending transaction confirmations (like purchase confirmations or account changes), transactional emails help to build trust between the customer and the company.


Personalization and relevance

Transactional emails can be highly personalized and contain information that is relevant to the recipient. This increases the likelihood that the email will be opened and read.

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Cross-selling Opportunities

While their primary purpose is not promotional, transactional emails can be an effective opportunity to subtly introduce other relevant products or services to the customer.


Analytics and Tracking

Transactional emails allow businesses to track key metrics, such as open and click rates, which helps to better understand customer behavior and continually improve communication strategy.

Trusted by our customers

  • The Mailrelay system has been a solution to our marketing system, and the customer support was good, and fast. Customer support is also in Spanish, this enables more of our staff to make contact, the treatment is customized and they are connected throughout the working day, from 8-22 and give rapid assistance. You can send…
  • Mailrelay is an easy and efficient tool that has saved us a lot of time and internal IT and commercial resources that weused to have to consume. It allows us toadapt predesigned templates to our corporate style and we can send mailings with personalized fields instantly. It has helpedus with our client relationships.
  • We started using Mailrelay in early 2012 as part of an internal communications project and, after we saw that the system brought us good results,including design options, we ended up working with the software tocommunicate with the media and marketing actions. So far, we didn’t have any problems, even in the case of specificcampaigns, when…
  • We have to thank the support offered by the Customer Service Department ofMailrelay, to help us create and edit our newsletters. They helped us a lot in everything we needed to start sending our newsletters. The system stands out for its functionality, cost and easeto use interface. The support, in ourcase, was fundamental. Without the…
  • By using Mailrelay, i try to send email marketing campaigns more Professional and with a more attractive design, and with this system I can measure the results of the strategies. Thanks to its statistical system I can sort and track our databases, see the analytical results of our campaigns, etc. Another improvement is the fact that this email…
  • Thanks to Mailrelay we can manage our own offers and exclusive packages, in a very agile way. In addition, the support offered by Noé, from the beginning was excellent, fast and effective. This helps us manage the system more easily. Without this help, we would have taken longer to learn how to manage the platform.

Empower your business with reliable, personalized transactional emails.

Enjoy higher deliverability, enhanced customer engagement, and analytics.