I see that some postings have touched on this before, mostly about long tables breaking or rearranging.
My experience: in a long message, a gap appears at at certain place, cutting across multiple table-based columns, displacing text slightly and (more with a more significant visual effect), bumping photos or inline tables to positions above or below the gap. Parts of the message can be rearranged, but the gap stays in the same spot.
I have been using Litmus to test the design, and I noticed that in their image for Outlook 2010 cut off at just the same point as where the gap appears, which seems like too much of a coincidence.
My totally speculative question: Could this be some annoying byproduct of the Word HTML rendering, like some kind of vestigial page break or something?
It's bad enough the number of things Outlook is ignoring these days (margins and correct line spacing being two big ones for me--no suggested fixes I've seen have really helped), but having it throw in mysterious elements that break my layout like that is just crazy.
I've found the best way to avoid the break issue is to use multiple nested tables in each column (rather than nesting one table in a column and using multiple <tr>'s.).
Is the object to keep any single row from getting too long, or...?
Or I should say, any single table.
My habit has been to use one cell for a lot of content (heading and paragraph tags), only throwing in smaller tables to nest other pieces of content in and help with spacing.
Part of the difficulty I foresee with trying to break up a column of content into multiple tables is in the way the repeaters work. Clients can multiply those ad nauseam, so there's not much control over the length. I have a template where the column consists of several set sections that could be broken in to separate tables, but if they're asking for the flexibility of being able to do away with a section when they don't need it, the whole thing needs to consist of repeaters for it to be deleted, and I'm not sure that a table holding a section will fully collapse when all that section's repeaters have been deleted.
If you can email over the code I can take a look and make a few recommendations.