I have been trying to fix this for several hours now and I just can't find the problem.
I have this HTML email signature that should wrap on low resolution devices.
This is the layout with how it should look on large screen devices:

And this is the layout with how it should look on devices with small screens:

This is the markup:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
</head>
<body>
<table width="100%">
<tr>
<td>
<table align=left width=160>
<tr>
<td>
<p>
<span style='font-size:12.0pt;font-family:"Times New Roman","serif"; mso-fareast-font-family:"Times New Roman"'>sep</span>
</p>
</td>
</tr>
</table>
<table align=left width=160>
<tr>
<td>
<p>
<span style='font-size:12.0pt;font-family:"Times New Roman","serif";
mso-fareast-font-family:"Times New Roman"'>ult</span>
</p>
</td>
</tr>
</table>
<table align=left width=160>
<tr>
<td>
<p>
<span style='font-size:12.0pt;font-family:"Times New Roman","serif";
mso-fareast-font-family:"Times New Roman"'>tur</span>
</p>
</td>
</tr>
</table>
<table align=left width=160>
<tr>
<td>
<p>
<span style='font-size:12.0pt;font-family:"Times New Roman","serif";
mso-fareast-font-family:"Times New Roman"'>ura</span>
</p>
</td>
</tr>
</table>
</td>
</tr>
</table>
</body>
</html>
The problem with web clients. For some reason, an additional HTML element is always added next to each of these four tables:

And here are the results:
MS Outlook 2007 (displayed correctly):

Apple GMail client (correctly displayed and wrapped, since this is a low-resolution screen):

- Outlook ( HTML-, , .):

GMail (- - Outlook):

, Litmus, . , , "" .
HTML:
- HTML-,
- (ctrl + A)
- (ctrl + C)
- MS Outlook 2007
- → → →
- → → .