accessibility - empty cells in accessible html tables

For an html data table in which each row represents an item (such as an email) would screen-reader users prefer empty table cells to be empty or to have a placeholder like a dash?

In my brief experience I think a dash would be useful because it keeps navigation consistent among the rows, but I want to make sure that this intuition is correct.

Answer

JAWS will read an empty cell as "BLANK" as noted here, which is why it's a good idea to avoid lots of empty cells (and table based BLANK layouts BLANK). Placing a dash will cause it to read the dash as well, which would make a lot less sense than BLANK.

I believe JAWS will also read a table cell with   inside as BLANK but I can't test this. It seems to read such elements as BLANK.

If the table is proper tabular data laid out correctly, BLANK is the logical way to read a blank row.

Also note if you leave a dash in an empty table cell it might make less sense to sighted users too. What does a dash mean for "Mother's Maiden Name"* for instance?

_{*Aside from Le Dasha}