Hupspot Email Subject Line Guide

Using Hubspot research on sales email subject lines, you can dramatically improve open rates by avoiding words that trigger spam filters, low trust, and instant deletion. This guide turns those insights into a practical, step-by-step process you can apply to every sales email you send.

Why Hubspot Research on Subject Lines Matters

Before you write another subject line, it helps to understand why certain words consistently hurt performance. The original Hubspot study analyzed millions of sales emails and revealed patterns in what gets ignored or flagged.

Common problems include:

• Spammy words that look like scams.
• Overly aggressive promises that reduce trust.
• Clickbait that creates a mismatch with the email body.
• Overused sales jargon that feels generic and impersonal.

By following the evidence-backed guidance from Hubspot, you can remove most of these issues in a few quick edits.

Words to Avoid in Sales Email Subject Lines

While the exact list in the Hubspot article is extensive, most of the low-performing words fall into a few clear categories. Removing these from your subject lines will instantly clean up your copy.

Hubspot Insight: Overly Promotional Words

Sales subject lines fail when they sound like late-night infomercials. Words that scream promotion can trigger spam filters or turn off busy prospects.

Examples of phrases to avoid include:

• “Buy now” or “Act now”
• “Once-in-a-lifetime”
• “Risk-free” when it sounds exaggerated
• “Free!!!” or multiple exclamation points

Instead, use straightforward language that describes the value or outcome you can deliver, an approach strongly emphasized by Hubspot research.

Hubspot Guidance: Vague, Hype-Heavy Phrases

Hype reduces credibility. Subject lines that rely on vague excitement often underperform because they do not communicate a concrete benefit.

Avoid phrases like:

• “Amazing offer inside”
• “You won’t believe this”
• “Shocking results”

Replace them with clear, specific statements such as “New benchmark data for your sales team” or “Ideas to shorten your sales cycle.” This aligns directly with the clarity-first approach recommended by Hubspot.

Hubspot Tip: Overused Sales Jargon

Jargon makes your emails blend into the noise. Prospects see the same language all day, so generic sales terms often lead to instant deletion.

Try to avoid generic subject line phrases like:

• “Touching base”
• “Quick question” when you have never met
• “Checking in” with no clear reason

Hubspot data consistently shows that specific, relevant language beats generic check-ins. For example, “Question about your Q4 pipeline” is far more compelling than “Quick question.”

How to Rewrite Subject Lines Using Hubspot Principles

Applying insights from Hubspot is easier if you follow a simple editing workflow. Use the steps below whenever you draft a sales email.

Step 1: Identify the Core Value

Start by writing down the single most important benefit in your email. According to Hubspot findings, clear value is your best asset in a crowded inbox.

• Are you sharing new data or benchmarks?
• Are you offering a relevant case study?
• Are you proposing a specific next step?

Summarize that benefit in one short sentence before crafting your subject line.

Step 2: Remove Problem Words

Now compare your draft subject line against the categories above and the source material from Hubspot at this detailed article on sales email subject lines.

1. Highlight any hype-based word.
2. Remove promotional language that sounds like an ad.
3. Delete extra punctuation such as multiple exclamation marks.

Your goal is a neutral, credible tone that lets the value speak for itself.

Step 3: Add Specific Context

Hubspot emphasizes the power of relevance. Make your subject line as specific as possible to the recipient and situation.

You can add context by including:

• The prospect’s role or team type.
• A shared event, such as a webinar or conference.
• A metric or outcome they care about, like “demo no-show rates” or “win rate.”

For example, update “Ideas for your team” to “Ideas to reduce demo no-shows for your SDR team.”

Step 4: A/B Test with Hubspot or Your CRM

If you use Hubspot or another CRM, run simple A/B tests to compare subject line performance. Even small changes in clarity or specificity can make a noticeable difference.

To test effectively:

• Change only one element at a time, such as length or level of detail.
• Send each variation to similar audience segments.
• Measure open rate and reply rate, not just clicks.

Document what works so your team can build a subject line playbook over time.

Examples of Subject Line Makeovers with Hubspot Logic

Here are sample improvements based on the guidance inspired by Hubspot research.

From Hype to Clarity

Weak: “You won’t believe these sales hacks!!!”
Improved: “3 ideas to shorten your sales cycle this quarter”

The improved version removes hype and multiple exclamation points while highlighting a clear outcome.

From Generic to Specific

Weak: “Quick question”
Improved: “Question about your Q3 inbound lead targets”

This aligns with Hubspot findings that specificity and relevance boost engagement.

From Promotional to Value-Focused

Weak: “Act now for our best offer”
Improved: “New pricing benchmarks for B2B sales teams”

The improved line replaces urgency hype with informational value, which often feels more trustworthy.

Hubspot-Inspired Checklist for Every Sales Email

Before sending any new campaign, run your subject line through this short checklist built from Hubspot-style best practices:

• Does it clearly state a benefit or topic?
• Does it avoid spam-triggering words and hype?
• Is it specific to the recipient or segment?
• Is it concise while still informative?
• Have you tested similar wording in the past?

Keeping this checklist handy for your team can create consistent performance improvements over time.

Next Steps: Put Hubspot Insights into Practice

Strong subject lines are one of the easiest ways to lift your sales results, and Hubspot research offers a reliable foundation. Combine the evidence-backed word lists with an internal testing process, and you will steadily refine what works for your audience.

For more help optimizing your sales and marketing strategy beyond subject lines, you can explore consulting resources such as Consultevo, which focuses on data-driven digital growth.

Return regularly to the original Hubspot guidance and your own analytics, and continue iterating. Over time, you will build a library of proven subject lines that consistently earn more opens, replies, and revenue.