How voters may submit absentee/mail ballot applications varies by state. All states will permit a voter to submit an application by mail (usually via an official application form, which may be available online for download) or in person at a local election official’s office. Many states also allow applications by email (usually with a scanned application). In general, most states require the request to be in writing.
At least 19 states, however, offer an electronic alternative: online portals through which a voter can request an absentee/mail ballot. Depending on the state, this option may not need authorizing legislation, and can be adopted administratively.