To apply for a Vote By Mail ballot, voters may submit an online application through the State of New Jersey at https://voter.svrs.nj.gov/mib-request.
Voters may also apply using a paper application. You can either use the voter registration application, which does not require postage (https://nj.gov/state/elections/assets/pdf/forms-voter-registration/68-voter-registration-english-essex.pdf), or the dedicated Vote By Mail application, which does require postage (https://www.nj.gov/state/elections/assets/pdf/forms-vote-by-mail/vote-by-mail-english-essex.pdf).
Both applications are to be sent directly to the County Clerk.