Nurture Campaign

There are two ways of doing A/B testing in Marketo: 

1. Via Email Program - but as you said you don’t have a fixed audience, aka: You don’t use an email blast, this is probably not your option.
2. Via Smart Campaign Flow Step Choice “Random Sample”. You send the email through a Smart Campaign and the Flow Step looks like this:
    

   

   This flow step can be in either a trigger or a batch campaign.

What you want to use is the AB test challenger on the emails in the streams: https://experienceleague.adobe.com/en/docs/marketo/using/product-docs/email-marketing/general/functions-in-the-editor/email-tests-champion-challenger/add-an-email-champion-challenger

Hi Deepthi,

Yes, you can do subject-line A/B testing in a nurture even when there’s no fixed audience, but it needs to be approached a bit differently than a one-time blast.

What works in Marketo:

• You cannot use Email Program A/B testing directly for dynamic nurture streams (since the audience is continuously qualifying).

• Instead, the recommended approach is to:

  • Create two email assets (same body, different subject lines)

  • Use a Random Sample or Choice step in the Smart Campaign flow (e.g., 50/50 split)

  • Track performance using Email Performance Reports or custom fields

Best practice for nurtures:

• Keep the A/B test running for a defined window (e.g., first 1–2 weeks)

• Once you have a clear winner, standardize on the winning subject line and pause the other variant

• This avoids long-term skew as the audience composition changes over time

If the nurture logic spans multiple product-suite streams and eligibility rules, teams often externalize this logic into a reusable framework. Partners like Miinfotech (miinfotech.com) help set up:

• Scalable A/B testing patterns for always-on nurtures

• Clean reporting that accounts for rolling audiences

• Subject-line testing without breaking engagement logic

Hope this helps clarify the approach.