card companies). Rule # 5 - Return on investment is everything! In the end, what counts is how much money you made on the mailing.   A Real-Life Example of Direct Mail Mathematics   Today I received this email from a close marketing friend of mine who understands direct mail marketing mathematics. Hes planning a postcard marketing campaign. Follow his logic closely!   Dear David:   I got a quote on my postcards.   Two-color ink (dark blue and red) on 100# gloss stock, 5.5 x 8.5 size.   5,000 quantity... $867.00.   That comes to .1734 cents each.   Now, add postage of .37 cents (after June 30), and the total cost is .5434 cents each.   Total cost to mail 5,000 cards comes to $2717.00.   If I make $300 on a package, it will take 9 packages to break even on the initial mailing, not counting any reports or sales letters that need to be sent out.   9 orders divided by 5,000 pieces is a conversion rate of .0018.   If I got a 1% conversion, that would be 50 sales. At $300 each, would total $15,000. This is PROFITS... remember, my shipping and handling costs cover the printing costs also.   What if I made $400 per package? I only need to sell 6.79 to break even on the mailing. A 1% conversion would be $20,000 in profits.   Now, all of this assumes that my mailing list is accurate, which it isnt. The names and addresses are up to two years old, so I can expect a certain number of returns due to incorrect addresses, or forwarding numbers that have expired.   If I figure that say, 20% are incorrect (thats figuring pretty high), it still beats renting a list from a broker at 80 cents per name, and only being able to use the names one time.