What subject line should a follow-up email have?
Keep the original subject and reply in the thread. The recipient sees the whole context, their mail client groups it with your first message, and "Re:" is itself a signal that something is pending. Change the subject only when the thread is more than two weeks old, the original subject said nothing useful ("Quick question", "Hello"), or you are escalating to a different person. When you do change it, say what you need and by when in under seven words.
When to keep the original subject
- The first follow-up, and usually the second. The thread does the explaining.
- You are writing to the same person. A new thread looks like a new ask, or spam.
- The original subject was specific: "Proposal for Q4 content, 2 options" needs no improvement.
- The gap is under two weeks. How many days to wait before following up has the timing table.
When to write a new one
- The thread is stale, three weeks or more, and the subject no longer describes the ask.
- The original subject was vague. "Catching up" has nothing to follow up on.
- You are adding a deadline or a decision that did not exist before.
- You are going to a new person, such as their colleague or your contact's manager.
- It is the last follow-up and you want the subject to say so.
30 follow-up subject lines by situation
Replace the brackets. Each is under seven words and says what you need.
After a proposal or quote
- Re: [Project] proposal, any questions?
- [Project] proposal: decision by [day]?
- Next step on [project]
- Still interested in [project]?
- [Project]: two options, one line reply
After a meeting or call
- Re: [Topic] from [day], the two things we agreed
- [Topic]: your [item] when you have a minute
- Following up on [day]'s call
- [Deliverable] you mentioned on [day]
- Closing the loop on [topic]
After a job interview
- Re: [Role] interview, [day]
- [Role]: any update on timing?
- Thank you, and one question on [role]
- [Role] at [Company]: next steps
- Checking in on the [role] decision
Cold or sales follow-up
- Re: [Their company] and [the problem you solve]
- [First name], still worth a 15-minute call?
- [Their goal] by [quarter]?
- One idea for [their company]
- Should I close this out?
Unpaid invoice
- Invoice [number]: due [date]
- Re: Invoice [number], payment status?
- [Amount] invoice from [date], overdue
- Invoice [number]: anything holding it up?
- Final reminder: invoice [number]
Last follow-up
- Last note on [topic]
- Closing this out unless I hear back
- [Topic]: I'll stop chasing after this
- One final check on [the ask]
- Should I take this off your list?
Subject lines that get you ignored
- "Following up" with nothing after it. Says you want something, not what.
- "Gentle reminder" and "Just checking in". Everyone has learned to skip them.
- "URGENT" or all capitals, when it is not urgent for them.
- "As per my last email". Reads as a reprimand before they have opened it.
- A question mark with no question: "Thoughts?"
- Anything over about 50 characters. Phones cut it off.
The body matters more than the subject
A good subject earns the open; the first two lines earn the reply. Restate the ask in one sentence, offer an easy out, and keep it under five sentences. How to follow up on an email with no response has six templates for the body.
Or let the follow-up write itself
The hard part is not the subject line. It is remembering which of last week's 40 sent emails never got a reply. Momo AI keeps that list for you: every sent thread with no reply, flagged after your window, with the follow-up drafted in your voice in the same thread, original subject intact. You read it and tap Send, or do not. Free during early access.
