Outlook can't read HTML5 elements. Without any code to see, I assume you're using divs and outlookseparator
is a class.
This may come as a bit of a shock (it's a lot of text) but this is what you'll have to do to get what you want in outlook. You can modify it, but make sure everything (widths) adds up.
<table border="0" cellpadding="0" cellspacing="0" width="640" style="border-collapse:collapse; padding:0; margin:0px;">
<tr valign="top">
<td align="left" valign="top" style="border:1px dashed #e6e6e6">
<table border="0" cellpadding="0" cellspacing="0" width="640" style="border-collapse:collapse; padding:0; margin:0px;">
<tr valign="top">
<td width="10">
</td>
<td align="left" valign="top">
<table border="0" cellpadding="0" cellspacing="0" width="300" style="border-collapse:collapse; padding:0; margin:0px;">
<tr valign="top">
<td align="left" valign="top" style="font-size:14px; line-height:16px;padding-top:10px;padding-bottom:10px;">
<font face="Arial,'Helvetica Neue',Helvetica,sans-serif" color="#444444" size="2" style="color:#444444; font-family:Arial,'Helvetica Neue',Helvetica,sans-serif; font-size:14px; line-height:16px; -webkit-text-size-adjust:none; font-weight:normal">
TEXT!
</font>
</td>
</tr>
</table>
</td>
<td align="right" valign="top">
<table border="0" cellpadding="0" cellspacing="0" width="300" style="border-collapse:collapse; padding:0; margin:0px;">
<tr valign="top">
<td align="left" valign="top" style="padding-top:10px;padding-bottom:10px;">
<img src="http://somewhere.com/images/something.png" width="300" height="100" alt="" style="display:block;" border="0" />
</td>
</tr>
</table>
</td>
<td width="10">
</td>
</tr>
</table>
</td>
</tr>
</table>
By the way, using classes in an email is bad practice. It will look terrible in GMail, as GMail doesn't read style tags or external CSS.