Week 2: Subject Lines and the Open Decision#
The decision usually gets made before the body is ever opened.
What this lecture covers#
- the mechanism: descriptive vs. self-sufficient subject lines
- the test for whether a subject line survives on its own
- a composite example, and the fix
- what published data says about how common this failure is
The mechanism#
A subject line that describes the email asks the reader to open it to find out what it’s for.
A subject line that states the specific, checkable thing inside lets the reader decide correctly without opening anything.
The test#
Does the subject line survive being read on its own, stripped of the email underneath it?
- “Introduction” fails. It names a category, not this email.
- “Following up” fails, for the same reason.
- “Grant deadline moved to Friday” passes. It’s actionable without opening.
What “survives on its own” requires#
A reader can decide two things from the subject line alone:
- does this concern them at all
- does it need acting on now, or can it wait
A descriptive subject line answers neither, so the reader is left guessing, and resolving a guess means opening the message anyway.
Predict, then watch#
Before the next slide: “Following up” as a subject line, on its own. Does it survive? Talk to your neighbour, then check your answer against what the email underneath it actually says.
From: [Sender]
To: [Recipient]
Subject: Following up
Just wanted to follow up on my last email. Let me know if you had a chance to look it over.
Restates that a first email existed. Adds nothing the reader can act on.
Ambiguity is a below-average strategy, even though it’s the single most reached-for choice in the language.
The fix#
Rewrite “Following up” as: “Following up: still looking for 10 minutes on the Q2 pricing proposal before Friday.”
Answers what it’s about, why it’s relevant now, and what happens if the reader doesn’t reply. The original answers none of the three.
Look this up#
Find a “Quick question” or “Checking in” subject line in your own inbox, sent or received. Strip the body away. Would a stranger know, from the subject alone, whether it concerns them and whether it’s urgent?
Recap#
- the open-or-skip decision happens at the subject line, before the body
- “self-sufficient” means relevance and urgency are decidable unopened
- category subject lines (“Quick question”) underperform the average subject line in large-scale open-rate analyses, not just the best ones