Hey Robert,
We don't have a settings to turn off the logo in the e-mail but you could edit the email template file and remove the html codes for the logo area.
You can easily modify the e-mail templates now from the back end,
http://take.ms/JNYVr . I have removed the block of codes below for your email template and it will no longer contain a login in the e-mails now,
[gist]
<table role="presentation" aria-hidden="true" cellspacing="0" cellpadding="0" border="0" align="center" width="100%" style="max-width: 680px;">
<tr>
<td style="padding: 10px 0; text-align: left">
<img src="<?php echo $logo;?>" aria-hidden="true" border="0" style="width: 119px; height: auto; background: #dddddd; font-family: sans-serif; font-size: 15px; line-height: 20px; color: #555555;">
</td>
</tr>
</table>
[/gist]
P/S: You could also click on the preview icon to preview the e-mail templates,
http://take.ms/Vv6mW