/*********************************************************************** * Copyright (c) 2000-2004 The Apache Software Foundation.             * * All rights reserved.                                                * * ------------------------------------------------------------------- * * Licensed under the Apache License, Version 2.0 (the "License"); you * * may not use this file except in compliance with the License. You    * * may obtain a copy of the License at:                                * *                                                                     * *     http://www.apache.org/licenses/LICENSE-2.0                      * *                                                                     * * Unless required by applicable law or agreed to in writing, software * * distributed under the License is distributed on an "AS IS" BASIS,   * * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or     * * implied.  See the License for the specific language governing       * * permissions and limitations under the License.                      * ***********************************************************************/package org.hwmhere.email.impl.util;/** * This utility class provides the set of header names explicitly defined in RFC 2822 * */public class RFC2822Headers  {    // See Section 3.6.1 of RFC 2822    /**     * The name of the RFC 2822 header that stores the mail date.     */    public final static String DATE = "Date";    // See Section 3.6.2 of RFC 2822    /**     * The name of the RFC 2822 header that stores the mail author(s).     */    public final static String FROM = "From";    /**     * The name of the RFC 2822 header that stores the actual mail transmission agent,     * if this differs from the author of the message.     */    public final static String SENDER = "Sender";    /**     * The name of the RFC 2822 header that stores the reply-to address.     */    public final static String REPLY_TO = "Reply-To";    // See Section 3.6.3 of RFC 2822    /**     * The name of the RFC 2822 header that stores the primary mail recipients.     */    public final static String TO = "To";    /**     * The name of the RFC 2822 header that stores the carbon copied mail recipients.     */    public final static String CC = "Cc";    /**     * The name of the RFC 2822 header that stores the blind carbon copied mail recipients.     */    public final static String BCC = "Bcc";    // See Section 3.6.4 of RFC 2822    /**     * The name of the RFC 2822 header that stores the message id.     */    public final static String MESSAGE_ID = "Message-ID";    /**     * A common variation on the name of the RFC 2822 header that      * stores the message id.  This is needed for certain filters and     * processing of incoming mail.     */    public final static String MESSAGE_ID_VARIATION = "Message-Id";    /**     * The name of the RFC 2822 header that stores the message id of the message     * that to which this email is a reply.     */    public final static String IN_REPLY_TO = "In-Reply-To";    /**     * The name of the RFC 2822 header that is used to identify the thread to     * which this message refers.     */    public final static String REFERENCES = "References";    // See Section 3.6.5 of RFC 2822    /**     * The name of the RFC 2822 header that stores the subject.     */    public final static String SUBJECT = "Subject";    /**     * The name of the RFC 2822 header that stores human-readable comments.     */    public final static String COMMENTS = "Comments";    /**     * The name of the RFC 2822 header that stores human-readable keywords.     */    public final static String KEYWORDS = "Keywords";    // See Section 3.6.6 of RFC 2822    /**     * The name of the RFC 2822 header that stores the date the message was resent.     */    public final static String RESENT_DATE = "Resent-Date";    /**     * The name of the RFC 2822 header that stores the originator of the resent message.     */    public final static String RESENT_FROM = "Resent-From";    /**     * The name of the RFC 2822 header that stores the transmission agent     * of the resent message.     */    public final static String RESENT_SENDER = "Resent-Sender";    /**     * The name of the RFC 2822 header that stores the recipients     * of the resent message.     */    public final static String RESENT_TO = "Resent-To";    /**     * The name of the RFC 2822 header that stores the carbon copied recipients     * of the resent message.     */    public final static String RESENT_CC = "Resent-Cc";    /**     * The name of the RFC 2822 header that stores the blind carbon copied recipients     * of the resent message.     */    public final static String RESENT_BCC = "Resent-Bcc";    /**     * The name of the RFC 2822 header that stores the message id     * of the resent message.     */    public final static String RESENT_MESSAGE_ID = "Resent-Message-ID";    // See Section 3.6.7 of RFC 2822    /**     * The name of the RFC 2822 headers that store the tracing data for the return path.     */    public final static String RETURN_PATH = "Return-Path";    /**     * The name of the RFC 2822 headers that store additional tracing data.     */    public final static String RECEIVED = "Received";    // MIME headers    /**     * The name of the MIME header that stores the content type.     */    public final static String CONTENT_TYPE = "Content-Type";    /**     * Private constructor to prevent instantiation     */    private RFC2822Headers() {}}