How do I uniquely identify a Java Mail Message using IMAP?

问题

IMAP Message in Java Mail is identified by it's relative position number which starts from 1.

refer, http://docs.oracle.com/javaee/1.4/api/javax/mail/Message.html#getMessageNumber()

Message number is a temporary details.

Is there a way to permanently uniquely identify a mail/message which accessing a mailbox via IMAP using Java Mail API which holds true across sessions ?

回答1:

Look at the UIDFolder interface, which exposes the IMAP UID capability.

回答2:

You can get a unique identifier for a message using the following code as an example

Folder folder = imapStore.getFolder("INBOX"); // get reference for inbox folder
UIDFolder uf = (UIDFolder)folder; // cast folder to UIDFolder interface
folder.open(Folder.READ_ONLY); // open folder
Message messages[] = folder.getMessages(); // get all messages
Long messageId = uf.getUID(messages[0]); // get message Id of first message in the inbox

来源：https://stackoverflow.com/questions/11435947/how-do-i-uniquely-identify-a-java-mail-message-using-imap