How to Thank a Mentor When You Leave a Job (Beyond 'Thanks for Everything')

Here's the short answer: the thank-you note to a mentor should not sound like a group email. Name one specific piece of advice you actually took. Say what you did with it. Say what you would have missed without them. Then ask for one line that stays open, a real thing, not "let's keep in touch."

A mentor is not a manager. Sometimes they were your manager once. Sometimes they still are. Sometimes they were three offices away and answered a Slack DM you sent at 10 pm three years ago and kept answering.

You are about to leave the company. You have written the resignation letter. You have booked the exit interview. Somewhere in the middle of that list is one line that says "thank the people who actually shaped how I work." That line is what this post is for.

Why the mentor note is different from the manager note

The manager thank-you is about the working relationship, the projects, the reviews, the meetings. The mentor thank-you is about the shaping. Someone told you a thing five years ago that you still hear in your head when you write a hard email. That is what the note has to name.

If you are also writing a note to your direct manager, that piece is covered in our guide to thank you messages to managers when leaving a job. Come back for the mentor note. The two are not the same message.

The four sentences that make a mentor note land

Four things belong in the note. In this order.

1. One specific piece of advice they gave you. Not "you taught me so much." A real sentence. "You once told me to always send the calendar invite first, even when the meeting felt like overkill."
2. What you did with it. "I have run every project since with a Monday standing invite, and it is the reason two launches did not slip."
3. The small unnoticed thing. The thing they probably do not know you noticed. "You always answered my DMs before 8 am. I don't think you ever mentioned it. I noticed every time."
4. One continued line. Not "let's keep in touch," everyone says that and almost no one does. Instead: "I would like to send you the draft of the review process I am building at the new place in three months. Would you have thirty minutes to look at it?" A real ask, a real timeframe.

Four sentences. Around 150 words. That is the whole note.

A worked example

Here is what one lands like.

Sarah, I wanted to send this before Friday. I have thought about it a lot this week.

You told me in the summer of 2022 that if the deck did not work at ten slides it would not work at forty. I have run every proposal since then against that rule. It has saved me twice from decks that would have embarrassed me.

You also always replied to my late-night questions before nine the next morning. You never made it a thing. I do not think I ever said out loud how much it steadied me in the first year.

I am starting at the new place on the 21st. I am going to build the same kind of monthly review process there in the first quarter. Could I send you the draft in October? Half an hour of your time would help me more than anything else I can think of.

Thank you. For all of it.

That is around 175 words. It names one specific thing. It has a real next step. It does not gush.

Send it before your last week

Send the mentor note five to seven days before your last day, not in the last hour. Two reasons.

First, your last week fills up. You will be booked into three hurried lunches, two team goodbye meetings, and an exit interview. The mentor note deserves a Tuesday-evening writing session, not a Friday-afternoon flurry.

Second, if the note lands well, the mentor might want to reply properly. Give them the week. Give yourself the time to read what they write back.

The one exception: if your mentor is at your current company and will be at the last-week goodbyes, send the written note the day before you also see them. Both. The written note is the record; the in-person moment is the punctuation.

The harder part is knowing who your mentors actually were

Most people can name one mentor. A few can name two. Almost no one can name the six people who actually taught them how to work over the past twelve months.

The recurring 30-minute 1:1 with the senior IC on another team. The person you kept sending drafts to. The engineer three years above you who reviewed your code and said something that changed how you thought about it. The PM you kept booking coffees with even though it was not a required meeting.

Those people are not on your org chart. They are on your calendar.

The list of who to thank before you leave is a calendar audit. You can build it in three minutes with It Was Great Working With You. Upload your calendar export from the last twelve months and it surfaces the quiet, repeated 1:1s that shaped you. The people you would have missed if you tried to write the list from memory.

Delivery method by relationship depth

The delivery matters. Not equally for everyone.

• Handwritten card. For the mentor whose advice you can quote from memory. Post it to their office address, or hand it over on a coffee. This is the highest signal a written note can carry.
• Email. For the mentor you worked with regularly and know well. Clean, four sentences, personal address. Copy no one.
• LinkedIn message. For the former mentor who has already left the company or is at a different organization. Same four sentences, plus a small note about how you are still tracking their work. If you are also planning a public farewell, this piece on the LinkedIn farewell post covers the timing.
• Public post or group email. Never for a mentor. A mentor gets a private note. A public post about them is about you.

If you are broadening the goodbye list to peers, close teammates, and clients, our list of the eight people to thank before you leave a job gives you starting lines for each category.

Edge cases you will actually hit

The mentor who already left the company. Send them the LinkedIn message. Reference the specific thing they said and where it still shows up in your work. Do not ask them to be a reference in the same note. Split those.

The informal mentor you never called that. Some of the best mentors are the ones you never gave the title to. Say it in the note. "You may not know this, but I have thought of you as a mentor since the launch in the spring of 2023. I did not want to leave without saying it." That sentence, sent, is what makes it real.

The mentor you disagreed with. Say the disagreement out loud. It respects them more than pretending it did not happen. "I did not agree with you on the pricing call, but I kept coming back to what you said about how to run a customer research week, and you were right about that. I want you to know that."

The mentor you are worried about being weird with. If the note feels weird to write, that is usually a sign that they mattered. Send it anyway. The awkwardness is on the sending side. On the receiving side, it lands as care.

What to leave out

Three things.

• The career retrospective. You will be tempted to summarize your whole time. Do not. One specific moment does more than a paragraph of summary.
• The next-job teaser. The note is not the place to announce the new role. If they know already, do not repeat it. If they do not know, they can read about it later.
• The empty stay-in-touch line. "Let's grab coffee sometime" is the dishonest version of a real ask. Either say "in three months when I have built the review process, could I send it to you?" or say nothing about staying in touch. Silence beats a promise you will not keep.

The last thing

Send the note. Then take twenty minutes and think about the second name. The third. The one you would have forgotten because they were on another floor. That is the harder list, and the shorter your last day gets, the harder it is to build from memory. It Was Great Working With You builds it from your calendar in under three minutes. Everyone you kept scheduling with. Nobody you missed.

Further reading: The people you'll forget to say goodbye to when you leave your job.