Washington election officials are sending out postcards this week to about 218,000 state residents who appear eligible to vote, but haven’t registered.

The mailing has a simple message that online registration is easy: “3 minutes. Click. Done.”

The postcard notes that the recipients aren’t on the voter rolls and that they are invited to register online or by mail by Oct. 5 in order to take part in the General Election. First-time Washington voters may also register in person at their county elections office by Oct. 26.

Washington residents are eligible to vote if they are at least 18, a U.S. citizen and not under custody of the Department of Corrections for a Washington felony.

“We hope these postcards will provide just the nudge for people to go online and get registered,” said Secretary of State Kim Wyman, the state’s chief elections officer.

The mailing list was generated by information from the Electronic Registration Information Center (ERIC), a non-profit organization of member states that helps improve the accuracy of voter registration lists and provides information on unregistered potential voters that states can contact.

At a minimum, the data include information from the Department of Licensing and voter records, including name, address, date of birth and last four digits of the Social Security number. Private data, such as DOB and last four digits of Social Security, are anonymized before being transmitted to ERIC. Cross-match with other member states also is done.

ERIC is able to identify voters who have moved within their state or out of state, those who have died, those who have duplicate registrations, and those who are potentially eligible to vote but are not yet registered. The Elections Division also regularly checks for voters who are behind bars for a state felony.

Wyman and state Elections Director Lori Augino said the ERIC information is extremely helpful in having a balanced program of voter outreach and keeping the rolls clean.

The postcard mailings are now in their fourth year. The cost is 23 cents per postcard, including printing and postage. This is the largest number mailed out since the initial mailing of 1 million in 2012. Only new contacts are including in the latest mailing.

Most of the postcards are in English. King County also provides about 79,000 in Chinese and Vietnamese. Adams, Franklin and Yakima provide over 11,000 bilingual English and Spanish.