Seems dubious to me, including the assertion about 3B Gmail accounts (unless Gmail added ~2.8B user accounts since January)
A new service, GiveBackMail, introduced this week, promises to give 25 percent of its profit to charity if users will route their e-mail activities through its Web site. “The more you use e-mail, the more money you direct toward your charity,” said Rambod Yadegar, who founded the service with his brother, Sam.
“They have such a significant user base,” he said, noting that Google has three billion Gmail accounts, while Yahoo and Microsoft have around 250 million e-mail accounts each. “We can have a significant impact in the nonprofit world by grasping only a very insignificant amount of their market share.”