For headers where a single value should be kept, it should be the first one instead of the last

[maxiwheat]

See mail-parser.js at line 396:

        // keep only the first value
        let singleKeys = [
            'message-id',
            'content-id',
            'from',
            'sender',
            'in-reply-to',
            'reply-to',
            'subject',
            'date',
            'content-disposition',
            'content-type',
            'content-transfer-encoding',
            'priority',
            'mime-version',
            'content-description',
            'precedence',
            'errors-to',
            'disposition-notification-to'
        ];

        headers.forEach((value, key) => {
            if (Array.isArray(value)) {
                if (singleKeys.includes(key) && value.length) {
                    headers.set(key, value[value.length - 1]);
                } else if (value.length === 1) {
                    headers.set(key, value[0]);
                }
            }

            if (key === 'list') {
                // normalize List-* headers
                let listValue = {};
                [].concat(value || []).forEach(val => {
                    Object.keys(val || {}).forEach(listKey => {
                        listValue[listKey] = val[listKey];
                    });
                });
                headers.set(key, listValue);
            }
        });

Comment says it should keep the first item, but instead we get the last one

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[maxiwheat]

This issue is stale because it has been open 30 days with no activity. Remove stale label or comment or this will be closed in 5 days.

Well, I still think this should be fixed