Once they're tweeted -- be it by a journalist or a rival politician -- they become TV ad, direct mail, and attack e-mail fodder.

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The ads are selected to match the subject matter of the e-mail, with Google's ad-placement software picking up on certain key words.

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With just a single magazine ad, he has already received 500 mail orders.

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But the carmaker knows a lot more than any TV ad can provide: their e-mail addresses and zip codes, for starters, which Chrysler forwards to local dealers.

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Most are still spending the majority of their ad dollars the old-fashioned way, on direct mail and print and online directories.

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The drama behind "Reply All, " a snippet from a spot that shows what happens when a worker hits the wrong e-mail button, and a creepy, soul-searching "Carma" ad (hint: don't run over the beavers), will finally be revealed this Sunday.

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These banner ad companies typically "hide" the recipient's e-mail address in the Web address of the graphic, so that their servers can later match the cookie to the recipient's e-mail address, Smith said.

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Mr Burmaster, believes any Microsoft-Yahoo ad network could run across all of the companies' platforms such as mail and social networks.

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McCain's campaign released an e-mail he sent North Carolina GOP Chairwoman Linda Daves that asked her not to run the ad.

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BlueTie's ads, called "featuretisements, " match an event someone types into his calendar or e-mail (such as a trip to Chicago) with, say, a possibly useful ad detailing flights that day.

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