Building an overly fancy HTML mail for a client. Code validates at http://validator.w3.org as XHTML 1.0 Transitional by direct input. Thing is Gmail displays gaps between
I know this is an older post, but this helped me, for anyone still looking:
Wrap your image(s) in a paragraph tag with margin, font-size, and line-height set to "0". I noticed that both Outlook and Gmail were adding erroneous paragraph, span, and font tags. Hope this helps someone else.