Year-end message for clients: how to write one they will remember

Some day in December, your client will open WhatsApp and find, one below the other, several year-end messages from companies they work with. Many will wish them a new year full of achievements, health and success. How many of them will recall something that happened between them and your company during the year? The year-end message for clients that stays in memory has one trait that is simple to state and takes work to deliver: only someone who lived that year with that client could have written it.

Year-end message for clients: searches peak in the last week

In the Google Trends data gathered by Mentoniano in October 2026, interest in the term "mensagem de fim de ano" stays close to zero from January to October. The monthly average for the last five years rises to 4 in November and jumps to 31 in December. Looking week by week, between October and December 2025, the peak of 100 shows up in the last week of the year. The scale goes from 0 to 100 and measures relative interest, without indicating how many searches were made.

Related queries also tell a story. Among the top ones are "mensagem de fim de ano para clientes" (year-end message for clients), "mensagem fim de ano empresa" (company year-end message) and "mensagem de recesso fim de ano" (year-end holiday closure message). Among the ones that suddenly grew are "mensagem de fim de ano emocionante" (heartfelt year-end message) and "mensagem de agradecimento final de ano" (year-end thank-you message). As we read it, many companies look for the text on the eve of sending it, with little time to think about what to say to each client. The rush pushes everyone toward the same ready-made phrases.

Why a company's year-end message sounds like all the others

The client notices. An Adobe Express survey of 1,007 consumers in the United States, conducted in December 2025, showed that 72% suspected they had received at least one brand email written by artificial intelligence. Among the reasons that most push readers away, 37% cited a generic message, and 37% said they trust a brand more when the email seems written by a person, even if it is less polished. The answers are self-reported, the sample is American, and Adobe sells creative tools, including AI ones.

A field experiment published in 2023 in the American Economic Journal helps gauge the size of the problem. Anya Samek and Chuck Longfield randomly assigned 500,000 new donors to public television stations and to a national nonprofit organization to receive, or not, a thank-you call. The calls followed standard industry practices. Fundraising professionals predicted the calls would increase donor retention by 80%. The measured effect was null.

As we read it, the study is a warning about the message written on autopilot, the one that follows the same script as every other company's. Saying thank you is still worth it, and the weight lies in what is said and in who says it.

What research on gratitude teaches those who write to clients

Researchers Amit Kumar and Nicholas Epley, of the University of Chicago, published four experiments on thank-you letters in the journal Psychological Science in 2018. Participants wrote to someone who had made a difference in their lives and tried to predict how the recipient would react. Then the recipients reported how they had felt. The writers underestimated the recipients' surprise and joy and overestimated their awkwardness.

One detail matters a lot to anyone who writes to clients. According to the authors, writers underestimate how surprised the recipient is "about why" they are grateful. The surprise lies in the reason, in the concrete fact that led someone to say thank you. Writers also underestimated how competent and warm the recipient would find them, and the authors point to worry about one's own ability to express oneself as a possible barrier to gratitude. The letters in the study were personal, so we treat the result as a clue for the relationship between company and client.

An older study, from 1995, points in the same direction. Bruce Rind and Prashant Bordia asked a server at an upscale restaurant in the United States to handwrite "thank you" on the back of some checks. The tip percentage went up on those checks. Adding her first name to the note changed nothing. The result suggests the effect came from the gesture of gratitude written by someone, a small cost for the writer.

How to write a heartfelt year-end message for clients

A heartfelt year-end message grows out of a fact the client recognizes right away. Here at Mentoniano, when we write a message like this, we start by listening: whoever serves that client knows what happened during the year, and that conversation provides the material for the text. A structure that works well has four parts:

• A moment of the year shared with that client, told in one or two sentences, with a date, place or situation.
• The thanks with the reason, saying what the client did and what it meant to your team.
• A sentence about the year ahead tied to the work you do together, with a commitment your company can keep.
• The signature of a person the client knows, with a name, along with the brand.

When it is time to write, each of these parts comes from the real history of the relationship, with dates and facts your team can confirm. Address the recipient by name and choose a moment the client would also remember without any help.

Written this way, no sentence in the message would work for another client. When the client base is large, sort clients into groups that went through similar situations and write a version for each group.

A client who receives three nearly identical texts on the same day draws their own conclusion. The care put into the text is the part of the message they can see.

Holiday closure message, WhatsApp and when to send

In Brazil, this message tends to arrive by phone. According to the Super Panorama Mobile Time/Opinion Box, published in June 2026, WhatsApp is on the home screen of 64.8% of Brazilian smartphones, and the Mobile Time report attributes part of this growth to brands using the app.

That is why we suggest sending two separate messages. The year-end holiday closure message is informational: service dates, on-call shifts, delivery deadlines and the contact for emergencies. The thank-you message deserves its own send, preferably before the last week of the year, when searches for ready-made texts peak and inboxes fill up. If your company is also sending a video, the fifth article in the series covers the Christmas video for clients, with the script and timelines.

The same logic applies inside the company. The first article in this series showed how the company party can help each person on the team see themselves in the year, and the fourth will cover the thank-you message the leader gives to employees.

Writing these messages is one of the jobs Léo Bento, our founder and scriptwriter, does for brands. He talks with the people who serve the clients, gathers the facts of the year and writes the text for each client or each group of clients, in your company's voice and with the signature of someone the client knows.

In the next article, the party's big screen: how to script the company's year-end video so the team sees itself in the year's retrospective.