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How to Generate Unique Subject Lines for Each Lead

Learn how to create personalized subject lines for every lead, test different types (offer, research, topic, source), and use them in your outbound campaigns for higher engagement and better A/B testing results.

Nora avatar
Written by Nora
Updated over 2 weeks ago

Can Twain generate unique subject lines for each lead?

Yes, Twain can generate unique subject lines automatically when you export your lead list from Twain. This unique subject line generation is built into the export feature and does not require additional manual prompting for each line.

Why it Matters:

  • Subject lines are the first thing prospects see — they decide whether your email gets opened.

  • Generic subject lines = lower open rates.

  • Personalized subject lines = higher engagement + a reliable way to run A/B tests across campaigns.

1. Generate unique subject lines

  • Twain now generates a different subject line for each lead automatically.

  • You can choose between 4 subject line types depending on your strategy:

    • Offer → highlights your value proposition (e.g., “Cut onboarding time in half”)

    • Research → pulls from insights you’ve referenced in the email sequence

    • Topic → focuses on the general theme of the message (e.g., “Scaling SDR performance”)

    • Source → references the original source or article that inspired the email


2. Preview before exporting

  • Twain shows a preview example for each type.

  • Each preview is just an example — the system generates unique versions for every single lead.

  • Confirm that the subject line type aligns with your campaign goal (e.g., awareness vs. conversion).


3. Set up an A/B test

  • To test effectiveness, split your lead list into segments. Example:

    • Group A → uses “Offer” subject lines

    • Group B → uses “Source” subject lines

  • Run both campaigns at the same time.

  • Compare key metrics:

    • Open rate

    • Click-through rate (if links are included)

    • Reply rate


4. Export to your outbound tool

  • Just like message sequences, subject lines export as custom variables.

  • Map them into your outbound platform (e.g., Smartlead, Outreach, Apollo).

  • Assign each variable to the first email in your sequence.


5. Measure, learn & optimize

  • Review campaign performance after a few days/weeks.

  • Identify which subject line type produced the highest open and reply rates.

  • Apply those insights to future campaigns.

  • Keep experimenting: rotate subject line types across campaigns to avoid fatigue.

Pro Tips:

  • Start with 2 subject line types at a time — don’t test all 4 at once, or results will be diluted.

  • Use “Source” subject lines when referencing recent insights or articles — they often feel more credible.

  • For direct outreach, “Offer” subject lines usually drive stronger reply intent.

Is it possible for Twain to generate subject lines with variables such as {nearest city}?

No, Twain does not support the use of variables like {nearest city} in subject lines. Asking Twain to generate subject lines using such variables will not work because it treats variables as placeholders, not as personalized phrases. If you need a variable-based solution, it’s recommended to use a simple formula in Clay or your campaign tool, rather than relying on Twain for this functionality.

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