Should you be putting more thought into your cold email subject lines? Hell, yes.

Do you have time to read through a million examples of email subject lines to find best? Hell, no.

We sifted through top blogs the best email subject lines of 2018, plus some fresh, real-life examples from our own SMEs – and pulled out the best of the best, so you don’t have to. Read on to see what’s hot, what’s not, and what has changed since the last time you looked.

What’s HOT

“The overall idea is stand out,” says Senior Sales Development Rep, Zachary Thompson. “People get so many emails. Sometimes, prospects will give me their personal email address, after a good phone call, because it will get lost if I email their business account!”


Example of a short cold email subject line: "Get ahead of Q4."“Every industry has something that’s top-of-mind,” says Demand Generation Specialist Dominique Catabay. “For example, we sell to sales and marketing, so the fiscal calendar year drives decisions for our prospects. I like to use references to “end of quarter” or “end your month strong.”

  • “End your month strong”
  • “Q4” Yep, that’s all.
  • “Budget talks”

“Think about seasonal or time-based terms that your prospect will be attuned to,” says Thompson. “For our prospects, an example might be ‘summer slump.’ The budgeting process is top of mind for our target market during October-November (and we want to get in during budget planning!).”

FOMO is real

Example of a cold email subject line: "What's in the box."Traditionally, we think of B2C subject lines about deals expiring at midnight or BOGO specials today only! The same principle applies for B2B email subject lines, with a professional twist.

“Things change, and professionals need to stay current. No matter how experienced you are, there are things you don’t know” Catabay says. “There will always be new technologies and best practices that you need to learn about. Offer new information.”

  • “XX email marketing trends you must know” This email subject line from Sumo got a 64% open rate by teasing a new trend.
  • “Before you write another blog post, read this” Another one from Sumo that offers the reader information they didn’t have before.

Read it: 8 Brilliant Basho Email Ideas for Cold Email Sales Outreach

How-to content

Example of a cold email subject line: "Inside Sales Toolkit. Your Guide to Sales Success."

“Anything that offers how-to info gets good opens,” Catabay says, “because we’re helping and disarming.” Not selling. “This works especially well with smaller companies, because they really are looking for assistance and trying to get better.”

  • “How to [set up an ABM strategy]” … or whatever the content is.
  • “How to Survive Your Next Overnight Flight” This example from Opt-in Monster also teases with a little mystery

Use personal “power words”

“Find 2-3 ‘power words’ for your prospect through research, and find a way to fit those into the subject line,” Thompson says.

  • “Idea for [topic the prospect cares about]”

“Find out where they went to school. I like to refer to a college sporting event or mascot name, especially during March Madness. Anything on LinkedIn, a business website, or press release is fair game.” (Personal information is not.)

Don’t give away too much detail

Image of a cold email subject line: "Heard you speak at a conference last week."“Share just enough information to get them interested,” Catabay says. “I’m always surprised to find that often, general subject lines work better than something more detailed.”

  • “Update?”
  • “Translations”

Thompson agrees. “I thought the more specific and in-depth I could go, the better … but that’s not actually the case for subject lines. I’ve found that specific isn’t better. Save the depth and detail for the content of the email.”

But be careful: The message itself still needs to apply. Being vague can be intriguing enough to click – but all the clicks in the world don’t mean anything if the prospect was expecting one thing and got something else.

As Act-On’s Nathan Isaacs says, “You can’t buy beer with open rates.”

Short and sweet

“Most people are opening email on their phones,” Thompson says. “I want my prospect to be able to see the whole subject line (no breadcrumbs) on a mobile device.” This differs between devices, so do some testing.

  • “Saw Hubspot on your website”
  • “Call tomorrow”

So what’s the ideal length for an email subject line?

The short answer, according to Marketo, is 7 words, although it differs wildly between industries and the quality of content.Chart breaking down the statistical likelihood someone will open your cold email based upon the number of words in the subject line. 7 is ideal.DiscoverOrg’s sales and marketing teams try to keep subject lines under 50 characters.

Use numbers (but beware the email spam trap)

Numeric numbers like dates and times work great – but they can trigger your email as spam and send you straight to the spam folder, damaging your domain authority and email deliverability.

  • “10 mins — [date]?” It’s a gamble, but asking for an appointment is a great use of numbers
  • “Cruisin’ 4 Critters is August 2nd – Register Today!” This example from Constant Contact leverages numbers to include a deadline – and a sense of urgency, without sounding spammy.

Hubspot offers a list of “spam trigger” words and suggests avoiding numbers like:

  • #1
  • 100% freeImage showing a frustrating office worker, illustrating the difficulties of cold emails.
  • 100% Satisfied
  • 4U
  • 50% off
  • Billion
  • Billion dollars
  • Million
  • Join millions
  • One hundred percent guaranteed
  • Thousands

Read it: What is Spam: The Truth about Cold Email


Image of a cold email subject line: "Don't re-invent the wheel."Dad jokes and eye-rolls can be silly. “But it’s a chance to be relatable!” says Catabay. “We wouldn’t want it to seem like some automated email that everyone gets – it feels more personal, person to person. I like to use puns in marketing emails.”

  • Don’t re:Invent the wheel” We sent this subject line in advance of the AWS re:Invent conference (Get it??)
  • Abra-cord-abra! Yeah, we said it.Hubspot shares this gem from Quirky. (We’re guessing hoping it’s about charging cords…)

Puns and humor are situational, so there’s no templates or playbook here. Keep things tasteful. If your dad wouldn’t say it – don’t say it.

Keep it real

Image of a cold email subject line: "Struggling with a long sales cycle?"Gimmicks work … for about two seconds.

  • “Question about [goal]” This one from Hubspot works because it’s real. You’re offering a solution, so you actually (hopefully) want to know about your prospect’s actual goals. Also, because the “goal” is different for everyone, no two subject lines will be the same.

Woman on a phone, illustrating a cold email or call.“These things are dynamic,” Thompson says, “and it’s hard to predict how long something will be ‘in’ or how long it will work. Gimmicky subject lines can give you a short lift in open rates, but the volume of email that’s sent in the B2B world is so overwhelming that novelty wears off, fast.

“Always be thinking about what you can do to stand out to the prospects, so you’re not just one of the other 300 other drip emails they have to deal with every single day.”

It’s about them (not you)

Best B2B Email-Subject-Lines“This should go without saying,” Thompson says, “but we still see it all the time. Subject lines should reference something the prospect cares about – not you or your product.” Their company, their goals, their pain points, their interests.

Mark Growth points to the “Cocktail Party Phenomenon: “The Cocktail Party phenomenon demonstrates selective attention. … Our brain is biologically designed to filter out what doesn’t interest us or what doesn’t benefit us.”

And you are not of interest. Not yet.

  • “Your annual goal”
  • “Ever Had This Problem? Tell me about it”

What’s NOT

Some email subject lines are so cringey they do actually get opened … and passed around the office for a chuckle – or worse, posted on LinkedIn. Not the kind of response you’re looking for!

  • “Do not open this email” Thou dost protest too much. We see right through you, desperate sender.Office worker on a phone, illustrating a cold email or call.
  • “Reminder”: Your prospect is already suffering anxiety from the real, actual “reminder” emails from their boss. Are you trying to give them hives?
  • “Friendly reminder”: Even worse. Are we friends now?
  • LOTS OF PUNCTUATION MARKS!!!!??? Especially when combined with ALL CAPS. Save the drama for your mama. Email panic attacks belong in the trash.
  • WeIRd CApiTaLiZAtioN: Spam. Delete. Rinse. Repeat.
  • “RE: Alligators” (or hippos, falling rocks, etc.): This worked for a hot minute in 2011.
  • “Thanks in advance.” Are you daring us to NOT do whatever it is you want? Cuz we will. That’s what passive aggression gets ya. And speaking of passive aggression…
  • “Did I misunderstand?” No you didn’t, Mr. Snarky-pants.
  • “Per my last email” Good thing you’re the only person who ever emails us, so we remember each of them.
  • “Any updates on this?” Um, do we owe you an update?

Of course, this list would not be complete without SalesFolk’s delightfully cringey email Hall of Shame.

At the end of the day, successful email subject lines should stand out from the crowd. It doesn’t matter how funny, personal, short, or otherwise amazing the email is, if it doesn’t attract enough attention to get opened. And, even more important, acted upon.

What techniques do YOU use to stand out from the crowd?

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Charity Heller
About the author

Charity Heller

Content Strategist, DiscoverOrg

Charity Heller, DiscoverOrg's content strategy manager, has been developing, composing, and editing content since age 2. Before her dive into content marketing, she founded and operated a book-editing company for 10 years. Charity has a B.A. in English literature, Professional Editing Certification from U.C. Berkeley, and she's a certified Project Manager.