in log4j-jakarta-smtp/src/main/java/org/apache/logging/log4j/smtp/appender/SmtpManager.java [236:245]
private void writeContent(
final LogEvent[] priorEvents,
final LogEvent appendEvent,
final Layout layout,
final ByteArrayOutputStream out)
throws IOException {
writeHeader(layout, out);
writeBuffer(priorEvents, appendEvent, layout, out);
writeFooter(layout, out);
}