"Rich-text format."

I'm reading your problem as "My files are MS Word .doc, and their Mac can't read them." Am I right?

If so, do a "save as" in Word to .rtf and email them one to try it.

If that still doesn't fly, copy/paste your text to Notepad and save it as 'plain text'. You'll lose formatting... but that's all you'll lose.

The 'zine I work on (and the one before, as well) sometimes gets submissions from Mac users. As long as they save their work in rtf, and make sure the filename includes the .rtf extension, my PC recognizes it and I can read it in Word (our guidelines page includes those very instructions). If it works in that direction, it just might work in the reverse, too.