HERNDON, Va. — E-mail was part of the emergency plan that Keys Federal Credit Union used to respond to Tropical Storm Fay as it bore down on Key West this weekend.

The $197 million CU’s staff decided Sunday afternoon to use the emergency notification system it has had for about two years to send an e-mail to 3,000 of the 15,000 members it has throughout the Keys, letting them know the branches would be closed but that all electronic services — ATM, online and phone — would remain up and running as long as conditions allowed.

The alert system is from DigitalMailer, a suburban Washington provider of e-statement and alert services to about 125 credit unions.

“With e-mail and text, members can access messages on their laptops or mobile phones. It doesn’t negate the need for recording phone messages or posting Web site notices, but it certainly enhances the effectiveness of communications and gets the word out quickly,” said the company’s founder and president, Ron Daly.