mj-button-padding.mjml

<mjml>
  <mj-body>
    <mj-section>
      <mj-column>
        <mj-button padding="2px 3px">
          Don't click me!
         </mj-button>
        <mj-button padding-top="1px" padding-right="2px" padding-bottom="3px" padding-left="4px">
          Don't click me!
         </mj-button>
      </mj-column>
    </mj-section>
  </mj-body>
</mjml>