You can send mail (SMTP) as the resource, like from a copier for scan-to-email.
zmprov ma existing.account@yourdomain.tld +objectClass zimbraCalendarResource displayName "MyDeviceName" zimbraAccountCalendarUserType RESOURCE zimbraCalResType Equipment
then flush the account cache:
zmprov fc account
zmprov ma account@yourdomain.tld zimbraPasswordMaxAge 0