Cells in Outlook 2007, 2010, and 2013

Question

I have this table where I need the distance between cells:

<table cellpadding="0" cellspacing="5px">
  <tr>
    <td><img src="http://placehold.it/100"/></td>
    <td><img src="http://placehold.it/100"/></td>
    <td><img src="http://placehold.it/100"/></td>
    <td><img src="http://placehold.it/100"/></td>
  </tr>
</table>

In Outlook 2007, 2010 and 2013, the interval is incorrect, while for other clients it looks just fine.

Outlook 2007, 2010 and 2013:

Other customers:

How to fix it?

Answer 1

<table cellpadding="0" cellspacing="5px">

it should be

<table cellpadding="0" cellspacing="5">