Formatting multi-value fields

{
    "$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
    "elmType": "a",
    "style": {
        "display": "=if(length(@currentField) > 0, 'flex', 'none')"
    },
    "attributes": {
        "href": {
            "operator": "+",
            "operands": [
                "mailto:",
                "=join(@currentField.email, ';')"
            ]
        }
    },
    "children": [
        {
            "elmType": "span",
            "style": {
                "display": "inline-block",
                "padding": "0 4px"
            },
            "attributes": {
                "iconName": "Mail"
            }
        },
        {
            "elmType": "span",
            "txtContent": {
                "operator": "+",
                "operands": [
                    "Send email to ",
                    {
                        "operator": "?",
                        "operands": [
                            "=length(@currentField) == 1",
                            "@currentField.title",
                            "='all ' + length(@currentField) + ' members'"
                        ]
                    }
                ]
            }
        }
    ]
}