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Generate subject lines for marketing emails using HubSpot AI

Last updated: June 11, 2025

Available with any of the following subscriptions, except where noted:

All products and plans

You can generate an effective and engaging subject line for your marketing email using HubSpot AI. This allows you to focus your time on refining and optimizing the content of the email campaign itself.

Please note: Please avoid sharing any sensitive information in your enabled data inputs for AI features, including your prompts. Admins can configure generative AI features in account management settings. For information on how HubSpot AI uses your data to provide trustworthy AI, with you in control of your data, you can refer to our HubSpot AI Trust FAQs.

Understand limitations and considerations

  • After you generate a pair of subject line suggestions, you can only generate new suggestions up to five more times for a single email.
  • The generated subject lines will be in the language you set on the Setup tab in the email editor. 

Understand AI-generated content best practices

  • Proofread and edit your AI-generated content before publishing it.
  • Edit AI-generated content to maintain your brand's voice and style.
  • Balance the use of AI-generated content with content written by a human.
  • While HubSpot has security measures in place, content assistant may occasionally generate incorrect, biased, offensive, or misleading information. Verify the accuracy of the output's content, especially any statistics or facts.
  • The large language model that powers content assistant tends to produce inconsistent results in non-English languages. HubSpot is working on better supporting these languages in the coming months. For now, use extra care in checking non-English content for accuracy and clarity.

Manage subject line assistant setting for all users

By default, the subject line assistant will be available to all users in your account. You can turn this setting off in your account settings:

  • In your HubSpot account, click the settings settings icon in the top navigation bar.
  • In the left sidebar menu, in the Account Management section, navigate to AI.
  • In the Access tab of your AI settings, click to toggle the Give users access to generative AI tools and features switch on.

Generate subject lines using HubSpot AI

To generate a subject line for your marketing email:

  • In your HubSpot account, navigate to Marketing > Email.
  • Click the name of a drafted marketing email.
  • In the email editor, click the Inbox tab.
  • Finish drafting the content of the email. 
  • In the Subject line section, click Generate.
  • In the dialog box, click Insert next to a suggestion to add it as your subject line. 
  • To see more suggestions like an existing suggestion, hover over the suggestion and click More like this
  • To generate new suggestions, click Generate new ideas.

You can also generate subject lines for your marketing emails using the HubSpot mobile app. Learn more about how to design and edit emails in the mobile app.

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