Can you test Email Subject Lines at 10% of List first, then the rest with Winning subject line

Hi Dona,

Yes, you can and there are a few ways to do this. Are you using an Email program or a default program? The email program has the ability to add tests built into it natively, while with the default program you'll have to use a Random Sample.

Hi, Dona.

You'll want to:
     1. Create an Email Program

     2. Create your email and add to the Email section of the program

     3. Click into the "Edit A/B Test" area you see in the lower, right corner of the above pic

     4. You'll then see this, where you can determine your A/B test criteria and the percentage to test before declaring a winner

Email Test - A/B Test - Marketo Docs - Product Docs

Thank you for all your help everyone!! So just to confirm, I would need to wait atleast 4 hours before the winning subject line could be sent?

I usually send my emails at 6:30 am, does anyone have a best practice on how/when i could set up my test, so i can try to send my emails around the same time?