The e-mail addresses — “tim—shawna” and “christyandbrian” — broadcast the couples’ commitment to all correspondents. If one spouse has a Twitter or Facebook account, the other is usually given the password. Often, spouses have separate work accounts where bad behavior could go undetected. However, the goal isn’t policing each other every minute, they say. Instead, they are doing whatever is possible to avoid keeping secrets.

“It’s not a matter of distrust,” said Ronda Hodge, 53, of Amesbury, Mass., an ice-cream maker who shares an e-mail address with her husband Tom, 60, a landscaper. “We really don’t have anything to hide from one another. We were friends first before we even dated so we’ve got that level of openness there.”

It’s impossible to know how widespread the practice has become.