5 Email Subject Lines for Sales Prospecting That Get Replies

Over 3 billion emails were sent daily last year*. 

That’s a communication tsunami. 

If that stat leaves you feeling overwhelmed, imagine how your prospects feel, drowning in their overflowing inbox each morning as your sales email bobs about among the flotsam of their ever-growing to-do list. 

Standing out from the inbox crowd these days means ramping up your game when it comes to writing sales prospecting email subject lines.

Time was, lines like “Sales inquiry” or “Request for a meeting” might have actually landed you a meeting 😱. Now, anything too salesy will get you cast into the 7th level of inbox hell (the spam folder) faster than you can say “Got 15 minutes to talk this week?” 

At Mixmax, we have to admit to having a slight advantage: We sell to salespeople, so our prospects know where we’re coming from. But that doesn’t mean our hard-working sales reps don’t rack their brains daily to come up with engaging subject lines.  

To give them (and you) a helping hand, we reached out to sales influencers and prepared a lifesaving list of the best cold email subject lines for sales prospecting that should help boost your email open rates.

Subject lines are important for sales prospecting emails because they are the first thing prospects see in their inbox. And the first thing prospects do each day is triage through that overstuffed inbox to decide what’s important and what’s not. 

If your subject line doesn’t hook them and make them want to know more, your email will be deleted without ever being read. 

Since 2020, the amount of emails everyone receives has gone up, which means their ability to read it all has gone down. Now, anything that sounds too played-out, demanding, or insincere is unlikely to make the cut. 

Writing short copy like email subject lines for sales prospecting requires not only good writing skills, but also a deep understanding of your prospective customer, their role, pains, and goals so you can write a good email subject line that strikes the right chord. 

Here’s how the experts do. 

The key to writing effective subject lines is avoiding anything generic, so lines like “Potential partnership,” “Potential synergy,” or “Partnership discussion” that used to work can now look too salesy.

Examples of the best subject lines for cold emails tick one or more of the following boxes: 

Piques curiosity

The best cold email subject lines don’t give too much away. As Daniel Kleinowski of Dairy.com says, “Aim to build curiosity but never satisfy it. If you provide all the context—‘we do this’ or ‘we help with this’—they’ll be like ‘No, we're okay’ without continuing to the meat of your email.”

So, sending a vague but appealing “Forecast” creates a mystery and raises the question “what forecast?” in potential customers’ minds. Only one way to find out, buddy…

You better satisfy that curiosity in your email, though. Misleading sales email subject lines trigger mistrust and can blow your chances of further engagement. A line like “Q4 email results” is likely to get you higher open rates, but if you don’t deliver on that in the email copy, they’ll feel duped.

Relevant 

Did we mention prospects are busy? Too busy to waste time on anything that doesn’t relate to their to-do list. That’s why compelling subject lines are relevant to their role, responsibilities, challenges, pain points, and goals. 

Emailing prospects to congratulate them on a recent publication or the fact that you went to the same school is all well and good, but really relevant subjects relate to the body of the email and show you’ve done your research and are worth their time. 

Basically, you can walk and chew gum at the same time. 

As Devin Reed of Gong notes, relevant topic + desired outcome = compelling subject, so you need to be specific. If your prospects are SDRs using sales prospecting tools like LinkedIn Sales Navigator, they’re unlikely to respond to something vague like “How to use LinkedIn,” but “Book more meetings with LinkedIn” is likely to make their ears prick up. 

The good thing about this approach is that you don’t need to be too clever. As Jason Bay puts it, instead of thinking about everything you can do to get your prospect’s attention, go minimalist instead. Write “boring,” obvious subject lines, like using their name, company name, a common problem, category, or industry.

If you’re sales prospecting to enterprises, remember to vary it to target different roles within the prospect’s company. “Opportunity” might work for a CFO, but a plant manager will be more focused on day-to-day production challenges.

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Includes keywords 

You obviously can’t know this in advance, but if your prospect uses keywords to filter and organize their inbox, including relevant ones in your subject can help send emails to an important folder in your prospect’s inbox. 

Promises value/benefit /opportunity

At Mixmax, when we see companies are hiring more SDRs for B2B sales prospecting, that means they could benefit from our sales engagement platform, which enables them to engage more prospects faster and personalize sales prospecting email templates at scale. So a good email subject line will reference that.   

Kyle Coleman recommends monitoring company news to see when they raise funding, but don’t just email to offer congratulations (and a thinly disguised desire for them to send some of that cash your way). Instead, do your research to understand why they raised that money, and what their priorities are for spending it. Then, craft a sale prospecting email subject line that ties your value proposition to their goals. 

Creates a sense of urgency

Triggering FOMO is a tried-and-tested sales prospecting technique (nobody wants to be the guy who turned down the Beatles). If you can make prospects feel they could be missing out by not reading your email, they’ll be more motivated to act. And even if they aren’t in a position to buy now, it gets you a foot in the door for when they are. 

Like curiosity-based subject lines, it’s vital your email copy does feature some kind of pay-off or time-sensitive offer.

Achieves pattern interruption 

Like a performing seal nearing retirement, prospects have been trained by unimaginative salespeople into a knee-jerk “delete-delete-delete” response anytime anything that looks like marketing lands in their inbox. To get a different reaction, you need to do things differently. 

At your own risk, try:

• Humor
• Weird grammar or formatting, like all lowercase
• A different tone or language to standard sales emails
• Hyper-short subject lines (like, one word, we dare you)
• Emojis

Obviously, whether these work will depend on your industry, but it’s worth playing around to see what gets results.

Includes a question

Questions demand to be answered and stop your prospect from simply thinking “yes/no” and scrolling past your email. 

Includes numbers

Numbers give prospects a break from text and are an easy way to promise value. Be honest, and thorough, and avoid using round numbers that’ll trigger their mental spam filters: “3 billion in revenue” sounds a lot less believable than “2.9 billion.”

Personalized 

Opinion is divided on this one: Some salespeople will tell you using the email recipient’s name in the subject line is too salesy, others swear by it to get their prospect’s attention. Experiment to see what works for you. Remember, though, that a personalized email always looks a lot less like part of a generic, impersonal blast. 

Remember, personalized doesn’t have to be the prospect’s name, it can also be their company name. 

Mixmax Sidebar within Gmail

Namechecks a shared contact

Referrals are a great way to warm up your first touch and establish common ground, trust, and a feeling of obligation to read your email (“Well, if Clare sent him…”). Like using the prospect’s name, a subject line referencing a shared contact is likely to make them pay more attention, and make your email seem more human.

References previous activity

If you’ve warmed up the contact beforehand on LinkedIn, or sent a voicemail, mention that in your subject line. As well as helping put a face to your name, it lets prospects know you’re focused on them as an individual, and persistent. (They’re probably going to have to hear you out sometime, so it might as well be now.)

Looks genuine 

Your subject line has one goal: start a conversation. It’s not a sales pitch, so avoid clickbait, marketing speak, cliches, empty buzzwords, jargon, and implied urgency or value where there is none. At best, these create the wrong impression. At worst, they’ll get you added to a spam filter.

As Will Allred of Lavender advises, “Write it like you would internally” to cut through the noise and keep their guard down.

The best cold email subject line examples read like you’re messaging a friend on social media. To create this impression, use lowercase and go easy on the punctuation (too much looks spammy). After all, when was the last time you messaged a friend like “Jeff, Increase Your Reply Rates by 90%!”

Keep it short

The ideal length for subject lines is 1-3 words. Anything longer looks salesy and requires too much mental effort to process. Short subject lines also read better on a mobile device, which is where most content is consumed these days.

Used by real salespeople. It doesn't get better than this. 

Subject lines to pique curiosity

These mysterious cold email subject lines are designed to get your prospects reaching for “open” to find out what’s inside: 

1. Was researching [prospect company name] and…

2. This can’t be right

3. I might be wrong

4. Does this work for you?

5. New year, new strategy

6. Your thoughts

7. Open to this?

Subject lines that sound internal / reference pain

At Mixmax, we sell to salespeople, so many of these lines would work for us, and serve as relevant keywords. If you’re in a different industry, just switch them out for ones that are relevant to your prospects.  

8. Sales copy

9. Sales cadences

10. Sales emails 

11. Email data

12. Personalization data 

13. Q4 email data

14. Focused on [goal]

15. [Area where you help]

16. Prospecting tools 

17. Outbound sales 

18. Response time

19. Hiring [role that could use your solution]? 

20. [Common industry problem]

21. Low response rates? 

22. [Year] [common industry] target

23. Revenue generation

24. Reply rate issues

25. Best-performing templates

26. Dashboard

27. Email tracking

28. Sequence editing

29. Performance overview

30. Prospecting issue

31. Low replies

32. Booking rate question

33. Call tasks

34. CRM update issues

35. Contact info missing

36. Context switching

37. Sequence writing

38. Cold calling

39. To-do list

40. Enough admin work

41. Data hygiene

42. Duplicate data

43. Repetitive tasks

44. missing data
(try all lowercase)

45. Check it out

46. Look at this

47. Here's the [industry] report

48. Saw this

49. This might help

50. Yesterday's news

51. You can use these

52. Listen to this

53. Proposal

54. Check out this article

Subject lines that promise value/benefit/opportunity 

55. Opportunity

56. Opportunity for [prospect company name]

57. More email responses

58. Send more emails

59. Idea for [pain point]

60. Idea for [prospect challenge]

61. [Prospect company name] revenue, [current year]

62. [Perform common task] better

63. [Benefit] for [prospect company name]

64. New [prospect responsibility] strategy

65. All-time revenue record for [prospect company name]

Subject lines that achieve pattern interruption 

Go random, use humor, and play with formatting, grammar, and punctuation to jolt them out of the stupor most prospecting emails induce: 

66. [3 random, unconnected things from your email]
(like Sustainable + Jill + Q4)

67. tom it's tough
(says, “this person's so damn confident, they don't need to follow the rules!) 

68. Annoying?
(self-deprecating humor, as a breakup email if you’re getting no response)

69. Not selling NFTs

Subject lines that include a question 

70. Connect?

71. How do you deal with it?

72. Taking advantage of [benefit]?

73. Strategy for [common goal] at [company name]?

74. How did you do it?
(to congratulate them on a recent achievement)

Subject lines that include numbers 

75. 24/7

76. Q4 email results

77. 2.4% growth

78. 143% of quota

Personalized subject lines

79. [Prospect’s current challenge]

80. [What you help with] at [company name]

81. [Prospect company product]

82. [Article/post prospect published]

83. [Point from recent interview/podcast with company's CEO]  

Subject lines that reference shared contact 

84. [Referral Name] said to reach out

85. Spoke to [Referral Name]

86. [Referral Name] says hi

Subject lines that reference previous activity 

87. Voicemail follow-up

88. New idea

89. Thought about what you said

Hyper-short subject lines 

90. Growth

91. Growth + [company name]

92. Revenue boost

93. [Prospect’s competitor company which is also your customer] + risk

94. Heads up

95. [Referee’s name]

Bonus: "Boring" subject lines 

Source: Jason Bay, Outbound Squad

If you’ve been paying attention, you may have noticed that not all of these subject lines strictly adhere to our advice 😕. Before you fire off a strongly worded email to our complaints department, that’s because what works for prospects in one industry doesn’t always work in another. Achieving healthy email open rates, therefore, takes time, practice, and patience. 

Start by looking inward: Talk to people in your company who occupy similar roles to your prospects. Ask which sales prospecting email subject lines get them to click open and why. Then, scour your own inbox to compare incoming cold emails with marketing ones to see what works on you. 

Once you’ve got an idea, start experimenting with the above formulas and approaches, and use a sales engagement platform like Mixmax that’s packed with customizable templates that autofill with prospect data from your CRM, making it easy to personalize and run multi-channel sequences at scale for better results.