RFC 6131

RFC 6131: Sieve Vacation Extension, "Seconds" Parameter 🎀

Okay bestie, RFC 6131 is a Standards Track doc from July 2011 (ISSN 2070-1721) written by R. George and B. Leiba, both at Huawei Technologies. Robins George and Barry Leiba wrote it, and it's an official IETF standard, so it's very serious and very official 💅. The header doesn't list anything it obsoletes or updates, so it's just doing its own thing ✨.

Abstract 🦋

This doc is a new add-on for the Sieve Vacation extension. It lets you send several auto-replies to the same sender in a single day by adding a :seconds parameter. Main character energy 👑

Status of This Memo 📜

This is an Internet Standards Track document 🔥

It's a product of the Internet Engineering Task Force (IETF) and it represents the consensus of the IETF community. It got public review and was approved for publication by the Internet Engineering Steering Group (IESG). If you want more on Internet Standards, check out Section 2 of RFC 5741 🌸

For the current status, any errata, and how to give feedback, go to http://www.rfc-editor.org/info/rfc6131 💜

Copyright Notice 🌈

Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved.

This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) as they were in effect on the date of publication. Please read these carefully, because they explain your rights and restrictions for this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty as described in the Simplified BSD License 🫶

Table of Contents 🍓

1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 2
  1.1.  Terminology Used in This Document . . . . . . . . . . . . . 2
2.  The ':seconds' Parameter  . . . . . . . . . . . . . . . . . . . 2
3.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
  5.1.  Registration of Sieve Extension . . . . . . . . . . . . . . 4
6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
  6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
  6.2.  Informative References  . . . . . . . . . . . . . . . . . . 5

1. Introduction ✨

Okay so the Sieve [RFC5228] Vacation extension [RFC5230] lets you automatically reply to incoming emails. Its ":days" parameter limits auto-replies to the same sender to one per [n] days, for a set number of days. But sometimes you want more granularity, like if you want "vacation" replies to go out more often 💅

That's where this extension comes in. It defines a :seconds parameter for those situations, and it's giving precision 🧚

1.1. Terminology Used in This Document 💖

The upper-case key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Those are the official rule words, so read them carefully 🙈

2. The ':seconds' Parameter 🦋

The whole point of :seconds is to set the minimum time gap (in seconds) between consecutive auto-replies to a given sender. The :seconds value, if you give one, is used instead of :days and works in a similar way (see the Vacation extension [RFC5230] for the details) 🌸

You can only use one of :days or :seconds. Using both in the same vacation action MUST result in a Sieve processing error. So don't try to use both at once, bestie 💀

The capability string for this extension is "vacation-seconds". Note that "vacation-seconds" implies "vacation", so a script with "vacation-seconds" in its "require" list can leave "vacation" off that list 🫶

The time value is in seconds. It MUST be greater than or equal to 0 and less than 2**31. All valid values, from 0 to 2**31, MUST be accepted without error. Sites MAY define a minimum effective value and/or a maximum effective value. If a site decides to do that:

1. Call the value specified "v(spec)".
2. Call the minimum effective value "v(min)".
3. Call the maximum effective value "v(max)".
4. Call the actual effective value used by the processor "v(eff)".
5. The following apply for determining v(eff):
   • If 0 <= v(spec) < v(min), then v(eff) = v(min).
   • If v(min) <= v(spec) <= v(max), then v(eff) = v(spec).
   • If v(max) < v(spec) <= 2**31, then v(eff) = v(max).

If a site imposes a maximum effective value, that value MUST be at least 86400 (one day) ⏰

If you use :seconds 0, it means every auto-reply gets sent, and there's no attempt to suppress consecutive replies. This is different from the base vacation spec, which doesn't allow a time period of zero (:days 0 is forbidden). The change is needed so an auto-responder can work (see [RFC6133], and check out example 4 in section 3 of that document, especially) 🎀

If you leave out both :seconds and :days, a site-defined interval is used (see [RFC5230]) 🌈

Usage:

vacation [":days" number | ":seconds" number]
                [":subject" string]
                [":from" string]
                [":addresses" string-list]
                [":mime"]
                [":handle" string]
                <reason: string>

3. Examples 🍓

Here's the first one. It automatically replies to senders saying the recipient is in a meeting. Multiple replies to the same sender only get sent every half hour (1800 seconds) 🧚

require ["vacation-seconds"];
vacation :addresses ["tjs@example.edu", "ts4z@landru.example.edu"]
         :seconds 1800
         "I am in a meeting, and do not have access to email.";

The second one sends an acknowledgment for every message received. A :seconds value of zero replies to every message, with no removal of duplicates to the same sender. This needs the Sieve engine to allow an interval of zero. If it doesn't, and it imposes a minimum value, then not every message will get an auto-reply 👑

require ["vacation-seconds"];

vacation :handle "auto-resp" :seconds 0
    "Your request has been received.  A service
     representative will contact you as soon as
     possible, usually within one business day.";

4. Security Considerations 🔥

The security considerations for the Sieve Vacation extension [RFC5230] apply equally here. On top of that, implementations SHOULD consider how many auto-replies could be generated by allowing small values of :seconds (including 0), and they MAY impose additional limits on that number. For a fuller discussion, check the Security Considerations section of RFC 3834 [RFC3834]. This one is serious, babe, so don't skip it 💀

5. IANA Considerations 💜

5.1. Registration of Sieve Extension 🦋

This is the registration template that goes to IANA:

To:  iana@iana.org
Subject:  Registration of new Sieve extension
Capability name:  vacation-seconds
Description:  adds the ":seconds" parameter to the Sieve Vacation
   extension.  Implementations that support this MUST also support
   "vacation".
RFC number:  RFC 6131
Contact address:  The Sieve discussion list <sieve@ietf.org>

6. References 🌸

6.1. Normative References ✨

[RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
           Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC3834]  Moore, K., "Recommendations for Automatic Responses to
           Electronic Mail", RFC 3834, August 2004.

[RFC5228]  Guenther, P. and T. Showalter, "Sieve: An Email Filtering
           Language", RFC 5228, January 2008.

[RFC5230]  Showalter, T. and N. Freed, "Sieve Email Filtering:
           Vacation Extension", RFC 5230, January 2008.

6.2. Informative References 💖

[RFC6133]  George, R., Leiba, B., and A. Melnikov, "Sieve Email
           Filtering: Use of Presence Information with Auto-Responder
           Functionality", RFC 6133, July 2011.

Authors' Addresses 🧚

Robins George is at Huawei Technologies in Bangalore, Karnataka 560071, India. The phone is +91-080-41117676 and the email is robinsgv@gmail.com 🎀

Barry Leiba is also at Huawei Technologies. The phone is +1 646 827 0648, the email is barryleiba@computer.org, and the URI is http://internetmessagingtechnology.org/ 🌈