The code I'm using is:

<div><p><img src="http://i.imgur.com/Rh4nxrc.png" width= "45px" height= "45px" align="left" hspace= "5px"></p>
<p style="font-family: Helvetica,Arial,sans-serif; font-size: 11px; line-height: 12px; margin-bottom: 10px;">
        <span style="font-weight: bold; color: rgb(33, 33, 33); display: inline;">Name Last Name</span>
        </p>
      <p style="font-family: Helvetica,Arial,sans-serif; font-size: 11px; line-height: 12px; color: rgb(33, 33, 33); margin-bottom: 10px;"><span style="color: rgb(33, 33, 33); display: inline;">Arquiteta - </span>
      <span style="color: rgb(33, 33, 33); display: inline;">ICP Arquitetura</span>
      <span style="display: inline;"><br></span>
      <a href="mailto:contato@icp.arq.br" style="color: rgb(71, 124, 204); text-decoration: none; display: inline;">contato@icp.arq.br</a><span style="display: inline;"> / </span><span style="color: rgb(33, 33, 33); display: inline;">(xx) 9 555-555</span>
    </p>
    </div>

I've just tried to use here, in the question body, and it worked:

The problem looks to be in the signature system.

Thanks for any help.