core/homeassistant/components/imap/icons.json

{
  "entity": {
    "sensor": {
      "imap_mail_count": {
        "default": "mdi:email-alert-outline",
        "state": {
          "0": "mdi:email-check-outline"
        }
      }
    }
  },
  "services": {
    "seen": {
      "service": "mdi:email-open-outline"
    },
    "move": {
      "service": "mdi:email-arrow-right-outline"
    },
    "delete": {
      "service": "mdi:trash-can-outline"
    },
    "fetch": {
      "service": "mdi:email-sync-outline"
    }
  }
}