ahhh yes 
— when the content is too long the message gets clipped by gmail:
In a non-clipped email there’s an empty td to the left and right of the td width="650" (the td width="650" contains the content, and the left/right tds adjust their widths to fill the remaining space equally, which centers the content)
When the email is clipped, that right td isn’t there:
…so the left td adjusts to fill the available width, and pushes the content td all the way to the right…
I guess I can fix this by making each content block in the email center itself independently, then in the case of the email being clipped maybe only the clipped section is aligned incorrectly…