jodd-mail/src/main/java/jodd/mail/CommonEmail.java
public T attachment(final EmailAttachment<? extends DataSource> attachment) {
		attachment.setContentId(null);
		return storeAttachment(attachment);
	}
public T attachment(final EmailAttachment<? extends DataSource> attachment) {
		attachment.setContentId(null);
		return storeAttachment(attachment);
	}
Adds {@link EmailAttachment}. Content ID will be set to {@code null}.

@param attachment {@link EmailAttachment} to add.
@return this