Email subject lines deserve your time and effort. The most obvious reason why is that subject lines grab people’s attention, and they decide in seconds whether or not to read the email. The second reason is that subject lines helps give you, the email copywriter, clarity for what you want to say in your email body.

Professional email copywriters always make sure that their subject lines include the 4U’s:

- Unique – offers something totally different from anything else.

- Useful – communicates value

- Urgent – instills a desire to receive benefits NOW.

- Ultra-specific – is clear as to the specific benefits.

To get inspiration for your next email’s subject line, think of it like the headline of a news article, or a caption on a display ad.

Here’s some examples of email subject lines in my own inbox

"Whoa! We've just doubled your bonus savings"

- Unique – It’s a clever use of the onomatopoeia “Whoa” that makes it unique. They could just as easily said, “We’ve doubled your bonus savings”. But “Whoa” is the attention grabber that makes it stand out.

- Useful – Uhhh … yeah! Who doesn’t want doubled bonus savings?

- Urgent – “Whoa” adds that sense of urgency.

- Ultra-specific – Absolutely no guesswork what they did.

"$1,839 hiding in your email lists?"

- Unique – This is a big key. Do use numbers in your subject line. And always use odd numbers, never even, rounded numbers. $1839 is better than $1800 or $1840. What’s also unique is the concept of money “hiding” in an email list. That’s incredibly unique!

- Useful – Who doesn’t want to discover that they’ve got money hiding in their email lists? That sure motivated me to read the email.

- Urgent – Sure. $18 or even $183 isn’t all that motivating. But once you start talking about over a thousand dollars, then that flips a psychological switch in my brain and gets me excited to know more.

- Ultra-specific – That’s obvious. It’s not $1800. It’s $1839!

Let me tell you about Core Emotions too.

Professional copywriters call “core emotions” as ones that are deeply rooted in our psyche. These emotions are so deep-rooted that we react at a subconscious level.

Curiosity
Curiosity is one of the most used emotions in email subject lines. We are by nature curious beings. We can’t help ourselves. A well-written subject line using Curiosity is highly effective.

- "AVOID this American food that’s banned in Europe"

- "THIS chocolate is 15x healthier than kale"

- "Our highest-grossing creator is sharing her secrets"

Urgency
Also known as “FOMO”, the Fear of Missing Out. Fear is a Core Emotion, and the Fear of Missing Out is one of the most widely tapped variations of fear.

- "Last Chance to Save on All-Clad!"

- "Time is running out – watch the replay now"

- "Manny, only 24 hours left – this SALE is slipping away"

Humor
Everybody likes to laugh. Injecting humor into your subject lines are a great way to get attention. And you’ll brighten up someone’s day at the same time.

- "I got crickets in my computer"

- "Don’t worry – you won’t turn into Betty White"

- "DIY At Home Liposuction"

You try it now. Go through the subject lines of the emails in your inbox. Can you spot the 4U’s? Can you spot the core emotion? How might you improve an email subject using the 4Us? Just for the heck of it, could you take a subject line using a core emotion and re-write it using another?