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Swipe & tweak these top 10 📩subject lines

Swipe & tweak these top 10 📩subject lines

May 12, 2025

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Swipe & tweak these top 10 📩subject lines

Funny how everyone moans about cold weather, but the first day it hits 85 degrees folks start whining… “sure is hot.” We can’t be satisfied… unless we’re complaining.

Anyway, the 72-degree days of spring are behind us, but not the best email subject lines from the past month. Check out my top 10 list of subject lines that got me to open and engage.

Then, Monday Marketing News leans heavy into some tools and tool how-tos.

Poll: Do you use direct mail campaigns?

The Main Thing

Top 10 Email Subject Lines that Made Me Look & Open

After this list, I’ll drop a few findings of my own subject lines for Inbox Hacking that got your attention too.

We’ll start with my personal inbox though to see what kind of subject lines got my attention and caused me to open and read the email.

BTW, these are in no particular order…

New #1 longest-lasting car, Is Apple Pay safer than Zelle?

Putting the number sign in a subject line still works because few senders use it.

Homeowners Are Sitting on $34.7 Trillion in Equity—but Mortgage Debt Is Growing

Trillion! I’m all ears.

AI vs. Gen Z: The Hiring War Has Begun

This is an add-on newsletter from Scott Galloway. The cool thing about this newsletter is it has a “Pardon the Interruption” feel with two personalities comparing their takes on various topics. I open 80% of Galloway’s No Mercy / No Malice emails. I open about 40% of this new one. Starting a “bonus” newsletter is smart.

5 Stocks Part of the 2025 AI “Wealth Wave”

Wealth Wave is a phrase I’ve never seen, thus it stood out. Adding the quotation marks makes it seem super-important. It was from SMH News.

The "acquire once, profit forever" formula

Stacked Marketer used the quotation marks also. Profit forever is a hard phrase to resist. And there’s a formula! That means it is doable for dummies - I opened immediately😉.

📧 Boring newsletters make BILLIONS?

The first one to make the list utilizing an emoji. Interesting. Oh, and “boring” businesses have been on the trendy list for a few years now. Prolly Mike Rowe’s blue-collar stuff started it, even though there’s nothing boring about running a plumbing or painting business. Ask my dad, not Codie Sanchez, who acts like you can put these businesses on autopilot. Total lie.

⌨️ Gen Z still loves Tumblr

Tumblr news lures people in because it refuses to die. It’s the Dracula of tech bubbles.

📝 Axios Finish Line: Powerful one-liners

Mainly pulled me in to see if I could use any of the one-liners inside. I found one and swiped it to use later.

Friday 4: Weird SEO strategy

All about the weird. And the number “4” tells me I can scan this Copyblogger email in 12 seconds.

🚫The subject line on number 10 did not matter! Why?

Because it was a reply to a reply I wrote to a newsletter crew about one of their topics. What stands out is the sender name because it lists their name then “me 3” (showing the number of messages between us). The point is it’s vital to reply to readers who take time to reply to your email sends.

Ok, to wrap the Main Thing up, see the top-performing Inbox Hacking subject lines the past 30 days (in terms of open rate). Ranked in order of performance. The preview text is in brackets:

Inbox Hacking’s Top-Performing Subject Lines

#1 🏃‍➡️Be ahead of the AI curve [with HubSpot's newly acquired newsletter]

#2 Why brands like Feastables use PodPitch instead of PR agencies🤔 [no preview text used]

#3 How to use comparison advertising 🙂😟 [+15 ways marketers can use Claude’s web search]

I’d guess the top two got the highest open rates the past 30 days due to inserting mega-brands in the text (HubSpot and Feastables).

Alright, enough subject line wisdom slung your way. On to Monday Marketing News.

Smarter Sales Starts with Voice AI

AI SaaS Smartcat boosted answered calls by 24%, reactivated 15% more leads, and cut booking costs by 70%—all by deploying Synthflow Voice AI Agents. Automated calls and let their sales team focus on closing deals, not chasing leads.

This case study breaks down Smartcat’s strategy and results, offering practical guidance for teams like yours looking to scale outbound efforts, reduce costs, and turn more conversations into conversions.

Click below to read their story and get the full guide.

Get the full story