Your table columns are not uniformly even. You have 3 rows, the first 2 have 1 column and the last one has 2 columns. Even if you have the right percentages, it is better to have it distributed evenly. Such as have all 3 rows have or "take the space of" 2 columns.
What I mean by that is that instead of using widths, you should use colspan
. Also remove the width from the image, if you want its original size, it should get it by default.
<table style="width:550px;margin:0 auto;" cellspacing="0" cellpadding="0" border="0">
<tr style="margin:0; padding:0;">
<td **colspan="2"** style="font-size:12px; line-height: 12px; text-align: right; color:#5A99B1;">Click <b>here</b> for the online version</td>
</tr>
<tr>
<td **colspan="2"** style="height:10px;" cellspacing="0" cellpadding="0">
<img src="border-top.png" />
</td>
</tr>
<tr>
<td style="background-color:white;">
<img src="brugadalogo.png" />
</td>
<td style="background-color:white; text-align: right;">
<img src="msdlogo.png" />
</td>
</tr>
</table>
Hope this solves your issue.