jodd-mail/src/main/java/jodd/mail/CommonEmail.java
public T embeddedAttachment(final EmailAttachment<? extends DataSource> attachment) {
		storeAttachment(attachment);

		final List<EmailMessage> messages = messages();
		final int size = messages.size();
		if (size > 1) {
			// Add to last message
			final int lastMessagePos = size - 1;
			final EmailMessage lastMessage = messages.get(lastMessagePos);
			attachment.setEmbeddedMessage(lastMessage);
		}

		return _this();
	}
public T embeddedAttachment(final EmailAttachment<? extends DataSource> attachment) {
		storeAttachment(attachment);

		final List<EmailMessage> messages = messages();
		final int size = messages.size();
		if (size > 1) {
			// Add to last message
			final int lastMessagePos = size - 1;
			final EmailMessage lastMessage = messages.get(lastMessagePos);
			attachment.setEmbeddedMessage(lastMessage);
		}

		return _this();
	}
Embed {@link EmailAttachment} to last message. No header is changed.

@param attachment {@link EmailAttachment}
@return this
@see #storeAttachment(EmailAttachment)