Also, some airlines require passengers to book e-mail fares online or charge extra for reservations made by telephone.
Most of the major domestic carriers either have or are in the process of running an e-mail fare program, analysts said.
FareCompare offers a similar e-mail fare alert service, as well as an iPhone app and a Twitter feed, so you can choose how you want to be notified about deals.
Some viewers of the documentary mailed bus fares to Jennings, telling him to return to Canada.
The "flix" in Netflix, its largely forgotten DVD-by-mail business, fared a bit better than the company had projected, posting a loss of just 380,000 subscribers in the quarter, to 8.22 million.
As The Guardian noted, the Daily Mail didn't fare quite so well.
Travelocity also makes liberal use of e-mail to sell these fares to the nearly 25 million people who have registered with the site.
That service, which can be found on the site's home page, prompts users to type in their preferred destination and price limit, then sends an e-mail when that fare is available.
He said the notice led him to imagine invasions of privacy, like new floods of junk mail from travel agents offering fares to the places that he calls.
The e-mail messages list highly discounted fares to selected domestic and international destinations, usually for the next weekend or within 10 days.
One of its handiest features is a free weekly e-mail newsletter listing special Web fares that airlines have announced that week, saving you the trouble of signing up for each carrier's e-mail promotions.
