Short answer: someone who commented on a post about your topic gives you a reason to write. A bare "like" is a much weaker signal, worth a message only when it adds to something else. Talk about the topic of the post, not about watching its reactions, and ask a question that picks up what the person wrote.
Which reaction is worth a message?
Not all reactions are equal. Here is our reading, to confirm with your own results.
| Reaction | Signal strength | What you can do |
|---|---|---|
| A single like | Weak | Nothing, or an invitation with no note if the person is in your audience |
| Several likes in a week on the same topic | Medium | An invitation, then a message on the topic |
| A short comment | Medium | Reply publicly, then send an invitation |
| A comment giving an opinion or a question | Strong | A message that picks up what they wrote |
| A share with a comment | Strong | The same, quoting their angle |
The limit: a reaction shows interest in a topic, not a need or a budget. Some people like everything they read. That is why you cross-check their role and company before writing.
How do you write to someone who is not in your contacts?
LinkedIn only lets you message 1st-degree connections directly. A 2nd- or 3rd-degree person needs an invitation first (LinkedIn Help, accessed October 8, 2026). The message is prepared in two steps: the invitation, then the message once it is accepted.
If the person commented on a public post, replying to their comment is a first contact that needs no invitation. It is often the best way in: visible, short, and it does not look like prospecting.
Which message templates should you send?
Square brackets are for you to replace. Each message fits in three lines and ends with a question.
1. They commented on your post
Hi [First name], thanks for your comment on my post about [topic]. You said that [precise reprise of their idea]. How is it going on your side at the moment?
2. They reacted to the post of an expert in your field
Hi [First name], I read your comment on [expert's name]'s post about [topic]. Your point on [detail] made me think. Do you run into it day to day at [company]?
3. They reacted to a competitor's post
Hi [First name], I am interested in [topic], which you talked about recently. What would be the hardest part of it for you today?
In template 3, name neither the competitor nor the reaction. "I saw you liked X's post" makes people feel watched, and they back off.
Should you say you saw the reaction?
On your own post, yes, it is natural: thanking them is the reason for the message. On someone else's post, talk about the topic and leave the reaction aside. The safest move is to quote what the person publicly wrote, never a "like" you found in a list.
When should you not write?
- The person is outside your audience: student, journalist, competitor's employee, peer.
- Their only sign of interest is a like on a post unrelated to your offer.
- They just received a message from you: wait for the end of the sequence.
- Their comment is a public complaint: answer in the thread, not in private.
How does Sales Farmer turn these reactions into a list?
The Watchlist picks up the people who like or comment on the posts of the profiles you follow, and keeps only those who match your audience. At the validation step, each person shows their source, for example "commented on a post by". They also carry a Matches or To check label, and a heat level with the evidence behind it, such as "liked two posts this week". The invitation goes out without a note, then the first message is sent once it is accepted: you can edit it person by person. Nothing goes out before you click Launch.
The sorting is not perfect: the people marked To check exist for that reason. On a competitor's post, a person the AI is unsure about from their headline still matches, since they reacted to that post. The Watchlist follows 10 profiles on the Starter plan; reading competitor pages belongs to the Growth plan. For the full method, see the article on social selling from reactions.
FAQ
Can you see who liked a LinkedIn post?
On a public post, the reaction counter generally opens the list of people. You cannot always see everything, and LinkedIn has no native export of that list.
Should you write to everyone who liked a post?
No. Keep those who are in your audience and who did more than a single like. Writing to everyone gives a hollow message and a low reply rate.
Is it GDPR compliant?
Reactions are public, but that does not exempt you from telling the person where their contact came from if they ask. Our guide to LinkedIn prospecting and GDPR details the obligations.
How long after the reaction should you write?
Within the week, while the post is still in the feed. It is a field rule of thumb, not a measurement. Later, the person no longer remembers reacting.