March 26, 2019 Julia 16 minutes to read

Case Study. How to build a trigger mailing system with Mandrill

The client approached us with the task of transferring triggered emails from a self-written own system to an external triggered mailing service. We have revised, supplemented and transferred 308 letters to Mandrill and the work is still going on.

We’ve achieved 98.6% deliverability and not a single downgrade or hit by Mandrill filters over the whole period with over 200,000 submissions per month.

About Dobovo

Accommodation booking service for daily rent
  • Founding year2010
  • NicheMarketplace
  • GeographyUkraine


The Client approached us with the task of transferring trigger emails (email messages that are automatically sent to the user depending on their actions or inaction automatically) from their own self-written system to an external trigger mailing service.

At that time, the Client considered his mailing system to be outdated:

  • there was no letter design
  • there was no multilingual support
  • marketing analytics wanted improvement, including email marketing

One of the Client’s wishes was to outsource the whole process of developing triggers and their implementation.

While discussing the task, we split it into parts:

  1. Choosing the trigger mailing service.
  2. Making a complete refactoring of trigger emails: redesign, copywriting, adding the necessary functionality and marketing calls to action.
    When the Client approached us, new letters were being added, but they were being developed by a programmer and a tester without taking into account the marketing requirements.
  3. Separating the language versions (the Client had Russian and English versions simultaneously in one letter).
  4. Improving email marketing automation. Thinking over a strategy and infrastructure to further analyze how effective the mailing lists and newly developed triggers are. The Client’s self-written solution did not support the analysis of email opening, click-through rate, deliverability, spam complaints, etc.


On’s side:

  • Olga Rybalchenko, project manager and executor
  • Alyona Klamarchuk, Maksim Sokur, Maria Rybalchenko — executors

On Dobovo’s side:

  • Vladimir Bezludny — СТО
  • Oleg Muraviev — programmer
  • Olga Mialkivskaya, Maria Bikerskaya, Milena Avdeieva, testing, implementation

Special features

Dobovo is a daily rental marketplace that communicates with 2 types of users:

  • guests who book accommodation,
  • owners who rent the accommodation out.

Originally, trigger emails looked like this:

An example of a trigger email before our participation
  • a plain text email
  • including both Russian and English in one email
  • no link tagging, which makes it impossible to track the effectiveness of mailings in Google Analytics
  • no marketing elements: Call-To-Action buttons, FAQ links
  • no analytics in general, and it’s difficult to assess whether the letters are working for the business goals

Choosing the trigger mailing service

Dobovo has been sending trigger mailings through its server since the beginning of its activity.

Disadvantages of mailing through your own server:

  • There is no analytics system — link tagging, email opening tracking, getting into spam, reactions of different mailing systems.
  • A lack of A/B testing opportunities.
  • Non-responsive templates. Responsive template design is no longer a luxury, but a necessity. Mobile devices are gradually replacing the desktop: according to CampaignMonitor, 41% of emails are opened from mobile devices.
  • It is difficult to make changes to email templates. This has to be done either by a programmer or a back-end tester.

Choosing the external service

We were choosing between SendGrid services and Mailchimp + Mandrill. We opted for Mailchimp, and here’s why:

  • With the growth of the base, the Mailchimp email marketing automation system turns out to be cheaper than SendGrid.
  • Mailchimp gives you the opportunity to get Mandrill’s triggered email service almost for free if you pay for a basic Mailchimp account.
  • According to all tests, Mailchimp email templates are the most adapted for mobile devices, and their layout passes all tests.
  • Mailchimp and Mandrill make up one infrastructure, which is easier to maintain.

Case study: email marketing for

Integration via API or SMTP

For triggered emails, there are 2 main ways to integrate: API or SMTP. We talked about this in detail in the email marketing case from

We’ve set up trigger emails for 128 Client

  • Virtual dataroom provider

  • Online SEO tool

  • Consumer electronics brand

Briefly about the differences between SMTP and API integration:

SMTP Integration

In this case, ESP is used as a gateway to transfer the complete email template. Most often, this method is used if email templates are sent due to some kind of analytics or personalization systems, when the template is transmitted along with the content of the email, for example, from CRM or 1C.  

The downside of this approach is that it takes longer to send emails due to SMTP protocol limitations (queues, server response speed). It is not suitable for high load projects.

API Integration

API integration means that email templates are stored in ESP. The site transfers the variables to complete the templates.

Advantages of API integration:

  • Only variables are transferred, there is no need to store templates on your side.
  • Templates are easy to edit. The marketing team can edit emails without involving programmers.
  • It is suitable for A/B testing.

We chose API integration for Dobovo.

Trigger emails development stages

1. Design. Initially, the template was created through Mailchimp and passed to Mandrill. In the course of the 3-year-long work, these templates have been modified many times:

  • we optimized the layout;
  • introduced our own CSS styles;
  • added blocks with comments in order to make it easier to typeset in the futureь.

2. Content and texts for three language versions: ru, en, ua.  We completely revised the content for each email:

  • added the necessary calls to action;
  • changed the wording to convey the main purpose of the email;
  • selected links to the FAQ, which can be relevant to help the user in the email.

3. Terms of referenceAll TORs for triggers are stored in a folder on Google Drive according to the principle: 1 TOR = 1 file.

An example fragment of the terms of reference for emails

It is very important to keep all the TORs up-to-date: to make changes when new variables are added; and if the syntax of the variables has changed, reflect this in the TOR marking the date.

An example of a TOR update

Two types of variables in Mandrill

Mandrill has two variable syntaxes: merge tags and handlebars. The only difference is that for handlebars you do not need to specify the default text in the template.

merge tagsfor the name variable, for example, the template has a default value that will be replaced by the necessary one transferred via the API:

handlebars — no default values ​​required:

Template syntax

Conditional blocks

Mandrill supports dynamic content and conditional blocks. For example, you can set a condition to display a certain block if the value for some variable is passed, and to hide it if there is no value.

Example: if there is a name, we pass a comma after “Hello ..!”. If there is no name, only “!” is passed.

Here is a more complex example: we can display a message in the template that the booking was made at a discount if the user has a certain attribute.

We display this or that block according on condition:


If the number of elements can be more than one, then it is possible to set a cycle and the table will have as many rows or cells as is passed via the API:

On average, an email template has 3 to 20 variables, depending on the email complexity.

Client – ​​Agency interaction process

All development is carried out through the task tracker. 1 trigger = 1 task.

After transferring variables to API requests is completed and checked by the tester, the templates are published to Mandrill. When all the work on the email is done, the Client, on their side, switches email sending from the internal system to Mandrill.

On average, full development of a trigger on our side takes up to 3 hours.

Switching to Git Version Control

After two and a half years of work on emails, the Git version control system was introduced.

Git 2.0 — automatic publishing from git to Mandrill

We asked the Client to automate the system in order to publish emails without accessing the Mandrill web interface.

This was needed to:

  • Save time when publishing small changes.
    For example, change the logo in all links or remove the link to Vkontakte in a couple of hundreds of templates. We spend less time — the Client saves the budget on our pay.
  • Reduce the chance of error. No one’s hand will “twitch” when updating the template via copy-and-paste in the web interface. All errors can be traced and rolled back. At the same time, versioning is preserved and Mandrill keeps releasing the correct version of the email.
  • Store all templates with all changes in the course of work in a structured way. It is easy to restore them, track changes and maintain.

The Client implemented it. We really enjoy the integration. Guys from Dobovo, thanks for the integration via Git!

Trigger integration checklists

For each process, we create a checklist and demand that our colleagues complete it. The checklist for Dobovo triggers looks like this:

From time to time, it is necessary to check and test emails in case the mobile version has fallen off, or to see what mobile version tables look like.

In Mandrill, a live version of an email for each user is stored for 30 days, and you can see what exactly was sent to this or that user.

Mandrill keeps track of the last 100 successful API requests, so you can check the value of every variable sent. Hence, it is possible to detect errors:


As part of the electronic mailing list strategy, we reworked, supplemented and transferred 308 emails to Mandrill and continue to do so. Including for partner projects Dobovo and for the Turkish version of the site with all the content being translated.

The system works flawlessly. The Client enjoys 98.6% deliverability, without a single downgrade or hit by Mandrill filters for the entire period of time. The reputation is “Excellent” according to the system, with more than 200,000 sends per month.

An example email before

An example email after

Триггерное письмо - пример с переменными

Mobile version of a trigger email

Триггерное письмо - пример на мобильном

Dmitriy Malakhov

Co-founder of Dobovo project

Online apartment booking service about working with

That’s it. Now it’s time for you to incorporate trigger emails into your email marketing strategy.

Do you want to set up email marketing?

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