In her recent book, Going Rogue: An American Life, former vice presidential candidate Sarah Palin called an incident in which her Yahoo e-mail was hacked the “most disruptive and discouraging” of her campaign.

Anyone seeking better e-mail security may want to check out a service called StrongWebmail, which adds a stronger layer of protection than just a user name or password. Users can verify their login with a PIN code sent via telephone.

When creating a new account, users provide the service with a phone number. They then choose a password and a user name, which consists of a user-specified name followed by the “@” symbol and “strongwebmail.com.” Customers are then sent a three-digit PIN, which can be used for initial account access. Users also have the option of only using the out-of-band PIN security system when they are at an “untrusted” computer not recognized by StrongWebmail.

People might only use the system when they are away from home or the office, says company CEO Darren Berkovitz.

StrongWebmail also has other security features, including automatic anti-virus scanning of messages. E-mail is also protected with secure socket layer encryption, which creates a tunnel between a user’s computer and StrongWebmail’s servers. Of the major Web-based e-mail services, only Google’s Gmail currently offers such protection.

The service does not use targeted advertising, which some e-mail providers accomplish by scanning message content. The company says it stores messages on dedicated servers that are secured by firewalls and encryption.

The secure e-mail service also provides many of the features e-mail users have come to expect, including spam filtering, individual filtering of messages into specified folders, and automated response messages. Certain features surpass those available on some major free services. Customers can send messages containing 50 megabytes of data, a few times larger than with several other major providers. A calendar feature can also send reminders by both e-mail and telephone instant message.

To prove its own security, the company issued a challenge to hackers. But last year, the firm was forced to give a $10,000 prize to a group of hackers who, responding to that challenge, successfully hacked Berkovitz’s account. The group said it took advantage of a Web site cross-site scripting vulnerability. Berkovitz says steps have been taken to close the vulnerabilities that were found.

Berkovitz says demand for the service, targeted mainly at small businesses and individual executives, has been “strong” this year.

For people needing added e-mail security, StrongWebmail could be worth a look.

Pros. It significantly strengthens e-mail security with phone-based authentication. Other security features are also strong.

Cons. Phone authentication for e-mail could be burdensome. Some people might also object to the fact that they have to use the domain “strongwebmail” for their e-mail address.

  Where to get it. The service is available at www.strongwebmail.com. Plans are priced at about $5, $7, and $9 per month. Plans offer storage of 100 megabytes, 1 gigabyte, and 10 gigabytes, respectively.