Webform submission by email wrapped in table

After much delay did I upgrade one of my sites to the latest core and modules.

Much to my surprise and dismay are the mails I get from webform submission now wrapped inside two tables:
<TABLE cellSpacing=0 cellPadding=5 width="100%" border=0>
  <TBODY>
  <TR>
    <TD vAlign=top align=middle>
      <TABLE cellSpacing=0 cellPadding=0 width="100%" border=0>
        <TBODY>
        <TR>
          <TD class=htmlmail-body vAlign=top>
...

I don't see this kind of change with the contact form. I don't think this is an issue with webform, since I didn't upgrade that.

Is this possibly an issue with the html mail or mimemail module?