B2B Cold Email Subject Lines: What’s Hot, What’s Not

Should you be putting more thought into your email subject lines for B2B sales? The answer is “yes.” Do you have time to read through a million examples of B2B email subject lines to find the best ones? We’ll go ahead and assume the answer is “no.”

We sifted through top blogs to find the best cold email subject lines, plus some fresh, real-life examples from our own salespeople. In this post you’ll learn how to write a B2B subject line that converts. And while this post centers around sales prospecting, these best practices can be adapted for networking, internship, and general cold email subject lines. Let’s get into it.

Table of Contents

  1. Seasonality
  2. F.O.M.O is Real
  3. How-To Content
  4. Use Personal “Power Words”
  5. Don’t Give Away to Much Detail
  6. Keep it Short and Sweet
  7. Use numbers
  8. Use restraint when it comes to puns and jokes.
  9. Keep it real.
  10. It’s about them (not you).
  11. Cold Email Subject Lines To Avoid

Effective Cold Email Subject Lines

“The overall idea is stand out,” says ZoomInfo 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!”

1. Seasonality

Example of a cold email subject line.

“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.”

“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!).”

2. F.O.M.O is real.

Example of a cold email subject line.

Traditionally, we think of B2C subject lines about deals expiring at midnight or BOGO specials “(Today only!”) The same principle applies to 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.

3. How-to content

Example of a cold email subject line.

“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

4. 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.)

5. Don’t give away too much detail.

“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.”

6. Keep it 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 seven words, although it differs wildly between industries and the quality of content. ZoomInfo’s sales and marketing teams try to keep subject lines under 50 characters.

Chart showing the effectiveness of email open rates at different subject line character counts.

7. Use numbers (but beware of the email spam trap).

Numeric numbers like dates and times work great – but spam trigger words they can 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% free
  • 100% Satisfied
  • 4U
  • 50% off
  • Billion
  • Billion dollars
  • Million
  • Join millions
  • One hundred percent guaranteed
  • Thousands

[Continue Reading] How Email Sender Reputation is Damaged

8. Use restraint when it comes to puns and jokes.

Example of a cold email subject line.

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.

9. Keep it real.

Example of a cold email subject line.

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.

“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.”

10. It’s about them (not you).

Example of a cold email subject line.

“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.”

Cold Email Subject Lines To Avoid

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, the desperate sender.
  • “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: 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 B2B 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 cold email techniques do you use to stand out from the crowd?

Contact ZoomInfo today to learn more about improving your B2B marketing efforts. Our business database is the tool you need for more informed marketing decisions.