IMAP Extension for Returning Mailbox METADATA in Extended LIST (2024)

Status of This Memo

This is an Internet Standards Track document.¶

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.¶

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc9590.¶

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Table of Contents

[RFC5464] defines the GETMETADATA command that is used by an IMAP client to retrieve mailbox annotations. Sometimes, a client will have to look up the metadata for some or all of the mailboxes returned by the LIST command. Doing so in multiple GETMETADATA commands wastes bandwidth and can degrade performance if the client does not pipeline the requests.¶

This document extends the LIST command with a new return option, "METADATA", which allows the client to request all of the desired information in a single command. For each listable mailbox matching the list pattern and selection options, the server MUST return an untagged LIST response, followed by one or more untagged METADATA responses containing the mailbox annotations requested by the client. The untagged METADATA responses to an extended LIST command have the same syntax and semantics as those that would be returned by GETMETADATA commands on the same set of listable mailboxes (see Section 4.4.1 of [RFC5464]). As per Section 4.4 of [RFC5464], the server may return all requested annotations in a single METADATA response for each mailbox, or it may split the requested annotations into multiple METADATA responses for each mailbox.¶

If the server is unable to look up the annotations for given mailbox, it MAY drop the corresponding METADATA response. In such a situation, the LIST command would still return a tagged OK reply.¶

6. Security Considerations

This specification does not introduce any additional security concerns beyond those described in [RFC5258] and [RFC5464].¶

7. Privacy Considerations

This specification does not introduce any additional privacy concerns beyond those described in [RFC5464].¶

Authors' Addresses