25 InMail subject lines and what makes them work

A good InMail subject line is specific to the person, short enough to read in a notification (the Sellinger agent keeps it under 60 characters, although LinkedIn allows 200), free of clickbait and emoji, and promises nothing the message does not deliver. The 25 lines below follow five patterns: a reference to their work, a shared context, a plain question, a number, and a direct purpose. We publish no reply rate for any of them.

Skylead, SalesRobot, Expandi and Dripify each publish a list of InMail subject lines. This one is different in a narrow way: every line comes with the rule it follows, so you can write your own instead of pasting ours.

Why does the subject line carry so much weight?

An InMail has two public parts before the person decides anything: the sender's name and photo, and the subject. On a phone the subject is shown in a narrow notification, and long lines are cut off. That is the reason the Sellinger LinkedIn agent writes a subject under 60 characters even though LinkedIn's hard limit is 200. A subject that needs the 200 is a subject that is likely to be cut in the middle.

Compare this with a connection request. A request without a note has no subject at all, and the person decides on a name and a profile. An InMail is a bigger ask, because it reached them through a paid or earned credit rather than through a handshake, so what you put in that first line has to justify the interruption. The post on when to use an InMail, a connection request or an email covers the choice. This post assumes you chose InMail.

What are the five rules?

Every line in the pack passes the same five checks.

1. It is about them or their situation, not about you. A subject that starts with your company name is an advertisement.
2. It is under 60 characters, so it is less likely to be cut off in a notification.
3. It contains no clickbait, meaning no promise of a secret, no false urgency, no fake "Re:" and no emoji.
4. It is true. If the line says you read their post, you read it. If it says a mutual contact exists, one does.
5. The message delivers it. If the subject is a question, the first sentence of the message should be the context for that question.

The fourth rule is not a style note. The Sellinger agent is built to write one concrete thing about the person's work, taken from their profile and posts, and an opener that states an observation did better than one that asks a question in our own LinkedIn outbound, by 10 to 15 points of reply rate in the months we compared (see the Sellinger case study). That is a finding about chat messages, not about subjects, and we do not stretch it. It does tell you where to put effort: the specific, observed detail.

The 25 subject lines

Placeholders are in curly brackets. Fill them from the person's profile, never from a guess.

Pattern 1: a reference to their work

1. Your post on {topic}
2. {Company}'s move into {market}
3. Question on your {role} hiring plan
4. Saw the {product} launch
5. Your talk at {event}

Use these when you read something real. A launch, a post, a hiring page. The cost is research, and the Sellinger agent does that step for each lead, which is why this pattern is the default for it.

Pattern 2: a shared context

1. Fellow {community} member
2. Both in {industry} in {city}
3. {Mutual name} suggested I write
4. Same {conference} panel in {month}
5. From one {role} to another

These only work when the context is true and checkable. Number 8 is the strongest line on the list and the most dangerous: if the mutual contact does not know you, it is a lie that takes one message to expose. Never use it without their permission.

Pattern 3: a plain question

1. Who owns outbound at {company}?
2. Is {problem} on your list this year?
3. How are you handling {task} today?
4. Quick question about {their tool}
5. Are you still hiring {role}?

A question works when it is answerable in a sentence and the answer matters to you. Avoid the empty teaser, such as "Quick question", on its own. It is the most common clickbait on LinkedIn, and recipients have learned to skip it. In our own data, questions as openers did worse than observations, so if you can state the thing you noticed instead, do that.

Pattern 4: a number

1. 3 ideas for {company}'s onboarding
2. One change to your {page}
3. 2 minutes on {topic}?
4. {Number} replies from {their industry}
5. A {number} point gap in {metric}

A number makes a line concrete, and it makes the line a promise. Numbers 19 and 20 must be backed by a real figure with a source, from your own results or a named study, and you should have it ready when they ask. The Sellinger agent does not invent figures in any message, and neither should you.

Pattern 5: a direct purpose

1. Partnership idea: {their company} and {yours}
2. Intro request: {topic}
3. Invitation: {event} on {date}
4. Offer for {role} teams
5. Reference request

Direct subjects are honest and low on curiosity, which is the point. They fit recruiting, partnerships, event invitations and referrals, where the person already expects a purpose. In those cases a clear label beats cleverness. See the notes on LinkedIn outreach for recruiters.

What should the message do after the subject?

The subject earns the open. The body, in the Sellinger agent, is three to five short sentences with a target of 700 characters or less: one concrete thing about the person's work, a short reason for writing and what is in it for them, and one low friction question. No calendar link in the first message, no attachments, and plain text only, since LinkedIn does not render formatting in an InMail. The longer version of this is in how the agent decides between an invite and an InMail.

How do you test subject lines without fooling yourself?

We publish no InMail result, because we have too few sends to say anything responsible. So treat all 25 lines as hypotheses.

1. Pick two patterns, not five. With limited credits you can compare two at most.
2. Split a list at random, one half per pattern, with the same message body and the same sending days.
3. Send at least 30 per variant before you read anything. With fewer, one extra reply moves the result by three points or more.
4. Count replies, not opens. A reply is the outcome you want and the one you can count without guessing.
5. Repeat once with a different list before you change your default.

The reply and acceptance rate calculator does the arithmetic, and the InMail credit planner shows how many variants your credits can afford. If your credit supply is small, test with an Open Profile audience first, since those InMails do not cost a credit.

What should you never write?

• Re: or Fwd: on a message that is neither. It is deception, and it is quickly noticed.
• An emoji, a row of capitals or a dollar sign.
• A subject that names a price, a discount or "free" in the first words.
• A subject that implies a meeting already happened.
• The recipient's name in the subject, followed by a generic message. Personalising only the subject makes the mismatch obvious.

A checklist

• [ ] The line is about the person or their situation.
• [ ] It is under 60 characters.
• [ ] Every fact in it is true and checkable.
• [ ] The first sentence of the message answers it.
• [ ] I am testing two patterns, not five, with at least 30 sends each.
• [ ] I am not quoting a reply rate I do not have.