The "@" symbol. . . used by grocers and accountants throughout the English-speaking world to indicate a rate, or cost per unit, as in "10 gal @ $3.95/gal" [ten gallons at three dollars and ninety-five cents per gallon] has become the de facto delimiter in e-mail addresses, separating the user's name from the domain name.
Although the change from at meaning "for a given amount per" to at meaning "in a specified (electronic) location" comes fairly naturally to English speakers, it does not for native speakers of other languages, for whom neither "at" nor @ meant anything until e-mail came around. ...