Unfortunately, there is no way to guarantee the layout of an email on any particular client. Most modern email programs will display an email correctly, but some will display text-only (many webmail apps) or will interpret the HTML code in the email incorrectly. Macs are notorious for this. I looked into it at one point because one of my list recipients uses a Mac and as many forums as I read the general consensus seemed to be “Email is for conveying information, not pretty formatting”.

Your best bet is probably to just send it out and hope for the best. If the layout is in html, you might run it through the HTML Cleaner to get all the MS XML junk out of it (Mac can’t understand that).
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