Internet-Draft | Structured vacation notices | July 2025 |
Happel | Expires 8 January 2026 | [Page] |
This document describes a machine-readable format for conveying unavailibility information in email messages. This includes "vacation notices" of persons but also different forms of unavailibility for emails sent by programs.¶
Structured vacation notices are supposed to be used in conjunction with conventional, human-readable vacation notices in most cases. They are based on the forthcoming "structured email" specification defined in [I-D.ietf-sml-structured-email-03] and related drafts.¶
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A "vacation notice" (also known as "out-of-office notice" [RFC3834][RFC5598] or "-reply") is a short text message which is automatically sent in response to incoming mail, if the recipient is absent or otherwise unable to answer immediately. Its content is written by the absentee in advance and usually informs about the unavailibility and possible alternative contacts for urgent inquiries.¶
The email system will return this content as an automatic repliy to incoming email messages, based on conditions set by the absentee. The most commonly used condition is the time period, during which incoming messages should be automatically answered with a vacation notice.¶
Vacation notices have not been standardized as such. A partial, implicit specification is contained in [RFC5230], which specifies an extension to the Sieve email filtering language. The user interface of MUAs provides further formalization of the user input for a vacation notice. While all this happens on the side of the absentee, vacation notices received by communication paterns just appear as a regular, human-readable email message.¶
The goal of this specification is to allow absentees to include a machine-readable version of the vacation notice, so that their communication partners can be assisted by software when dealing with vacation notices.¶
While this specification may be used stand-alone, is aims to be compliant to the "structured email" specification ([I-D.ietf-sml-structured-email-03]) and its trust and security recommendations ([I-D.happel-structured-email-trust-04]).¶
The term "message" refers to "electronic mail messages" or "emails" as specified in [RFC5322].¶
The term "Message User Agent" (MUA) denotes an email client application as per [RFC5598]. Based on the role of the communication partners, one can further distiguish into "Recipient MUA" (rMUA) and "Author MUA" (aMUA).¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
Many systems allow to specify a time range, during which a vacation notice should be sent. Notably, this time range must not exactly match the actual absence time, even though this is probably the most common case in practice.¶
When realized using the Sieve vacation
extension ([RFC5230]), time periods are typically defined in conjuction with a currentdate
test ([RFC5260]).¶
We distinguish temporary and permantenty availability for considering the time periods of unavailability denoted by a structured vacation notice.¶
Temporary unavailabily for a certain time range is the most common case for vacation notices, typically specifying a start and an end date. Some systems also allow for an open-ended time period, leaving start or end date empty.¶
The specification of fixed workdays for a person or of service days for an organization is currently not supported by most systems.¶
Permanent unavailability can be seen as a special case of unavailability, in which a person or service will be no more available in the future. This is mentioned as part of the "Change of address" case in [RFC3834] and can already be modeled in some systems by leaving both, start and end date, empty.¶
Even though the corresponding mailbox will eventually cease to exist at some point, it is not uncommon that affected persons or services return a "permanent unavailability" message during a phase-out period.¶
A mailbox move is a special form of permanent unavailability. While the original mailbox will become permantently unavailable at some point, there exists a new mailbox replacing the former one (also mentioned in the "Change of address" case in [RFC3834]).¶
Reasons for this might be a name change in the local part (e.g., due to marriage) or a name change in the domain part (e.g., a company merge or renaming).¶
A "noreply" message is an internet naming convention, indicating that a sending mailbox is not attended and replies to that mailbox will likely be discarded. This fact is typically conveyed by the name of the email address ("noreply@example.com") and sometimes explained in the email body. It is typically used on machine-generated, transactional emails.¶
Noreply messages can be considered as a form of unavailability and hence fit into this draft. "Replacement" information as described in the data model of this specification can be used to point receipients to other communication channels such as a phone hotline.¶
The minimum data for a vacation notice is the actual notice content as specified by the absentee. It might be as short as "I am currently out of office".¶
This document specifies an RDF class UnavailabilityInformation
which is described in the following sections.¶
start
and end
are optional date fields in the format YYYY-MM-DDThh:mm:ssZ
following ISO 8601 ([iso8601]). Since both dates are fixed in time, they do not require timezone information for interpretation. Hence, the date MUST only be formatted in UTC.¶
availabilityPattern
is a text String with similar semantics as the Schema.org openingHours
property ([openingHours]). availabilityTimezone
is a text String with an identifier from the IANA Time Zone Database ([tzdb]). If an availabilityPattern
is set, the availabilityTimezone
property MUST be set as well.¶
Both start
/end
and availabilityPattern
might be used in parallel. In this case, the start
/end
dates override the availabilityPattern
in case of conflict.¶
A permanent absence can be signaled explicily using mailbox status information as explained below.¶
Vacation notice content may also contain information about if a message is automatically forwarded to a replacement person (isForwarded
), or details about replacement persons to contact for urgent inquiries (replacement
).¶
When considering organizational users or role accounts, a replacement can also be another organization ("While our doctor's office is closed, refer to Dr. Doe in case of emergencies"). Values of the replacement
property are of type Replacement
, which:¶
description
to add context for distinguishing multiple replacement options¶
availabilityPattern
and availabilityTimezone
¶
For a clear distinction of cases of temporary and permanent unavailability, senders MAY specify an unavailabilityType
property in UnavailabilityInformation
.¶
unavailabilityType
is text field, allowing for the following values:¶
temporary
(temporary absence/classic vacation notice; implicit default value)¶
permanent
(infinite absence / mailbox is not used anymore)¶
moved
(mailbox name has changed)¶
noreply
(mailbox is send only)¶
For any value which is not temporary
, potentially conflicting information from the end
date MUST be ignored. The start
date however MUST be considered if set.¶
For the use cases, we distinguish the absentee, willing to answer incoming messages with a vacation notice, and communication partner(s), which are sending messages to the absentee during or around the time of her absence.¶
The absentee might want to send vacation notices in two difference scenarios. Besides the common, dedicated vacation notice autoreplies, machine-readable vacation notices might also be added to regular email messages sent to communication partners ("preemptive vacation notice").¶
For adding a structured vacation notice in a common vacation notice message, a JSON-LD snippet using the UnavailabilityInformation
type defined in the previous section needs to be embedded in the text/html
representation of the vacation notice email (TODO sync with [I-D.ietf-sml-structured-email-03]).¶
In systems using the Sieve vacation
extension ([RFC5230]), text/html
body parts are supported when using the parameter to include MIME content (:mime
).¶
If the user interface already allows to set date ranges, the structured vacation notice data may be added or prefilled automatically, without extra user effort.¶
Structured vacation notices can support a second use case, in which information can be preemptively added to regular outgoing email messages by the absentee.¶
This may be helpful in three scenarios, if an absentee sends a message:¶
<a/>¶
For discussion, see also: https://github.com/hhappel/draft-happel-sml-structured-vacation-notices/issues/2¶
Structured vacation notices may be processed by the communication partner (resp. her MUA) in different ways.¶
If an incoming vacation notice contains structured vacation notice data, the MUA of the communication partner MAY extract and store this data.¶
Since the MUA can make sense of the structured vacation notice, it MAY also employ various forms of user assistance at its own discretion, such as:¶
As described before, the absentee may decide to add structured vacation notices in regular messages sent before, during, or after her absence.¶
When receiving such messages, the MUA of the communication partner MAY extract and store the structured vacation notice and MAY display the absence information.¶
If a communication partner wants to send a message to a person, for which a structured vacation notice has been received earlier, the MUA MAY inform its user about this upcoming or ongoing absence.¶
The following points should be considered when implementing (structured) vacation notices from a sender and recipient-side processing perspective.¶
Adding structured data to a vacation notice should be left as a choice to the user. A MUA SHOULD not add structured data to vacation notices without explicit consent or action of the user.¶
Vacation notices containing structured data which are sent to human readers MUST contain a human readable alternative version of the vacation notice using text/plain
and/or text/html
multipart/alternative
body parts.¶
Vacation notices sent between mailboxes that are known to be processed by programs only may just contain a structured vacation notice as their main message body part.¶
A MUA MUST ignore structured vacation notices with time ranges in the past.¶
If multiple structured vacation notices exist for a user, prefer the one from the most recently received message.¶
In the case of preemptive structured vacation notices, strip the structured data from the message when it is forwarded to a third party by the user.¶
< RFC Editor: before publication please remove this section and the reference to [RFC7942] >¶
This section records the status of known implementations of the protocol defined by this specification at the time of posting of this Internet-Draft, and is based on a proposal described in [RFC7942]. The description of implementations in this section is intended to assist the IETF in its decision processes in progressing drafts to RFCs. Please note that the listing of any individual implementation here does not imply endorsement by the IETF. Furthermore, no effort has been spent to verify the information presented here that was supplied by IETF contributors. This is not intended as, and must not be construed to be, a catalog of available implementations or their features. Readers are advised to note that other implementations may exist.¶
According to [RFC7942], "this will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. It is up to the individual working groups to use this information as they see fit".¶
This draft is implemented in an open source plugin for the Roundcube Webmail system [RC-SVN], partly based on the Roundcube managesieve plugin.¶
In particular when using structured vacation notices in conjunction with the Sieve filtering language, the security considerations of the corresponding RFCs should be taken into account:¶
Vacation notices expose certain potentially sensitive information to third parties, such as absence times, absence reasons and organizational details (such as replacement staff and their contact information).¶
For this reason, absentees are typically free to decide how much information they expose in the written text of their vacation notice.¶
Accordingly, software systems SHOULD leave absentees the same level of freedom when adding structured vacation notices and, e.g., not enforce the inclusion of certain information or even do so implicitly.¶
Information exposure might also be limited by restricting the usage of structured vacation notices to certain communication partners (e.g., using address book information [RFC6134] as discussed in [RFC6133]).¶
This document has no IANA actions at this time.¶
The following snippet shows a potential extension to the [SchemaOrg] vocabulary in [JSONLD] format.¶
Note that this is a preliminary specification only. Do not use examples in practice.¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "start": "2025-06-22T00:00", "end": "2025-08-22T00:00", "note": "I am currently on vacation." }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "start": "2025-06-22T00:00", "end": "2025-08-22T00:00", "availabilityPattern": "Mo,Tu 12:00-15:00", "availabilityTimezone": "Europe/London", "note": "I am currently on vacation." }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "availabilityPattern": "Mo,Tu 12:00-15:00", "availabilityTimezone": "Europe/London", "note": "I am in office Mondays and Tuesday afternoon." }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "unavailabilityType": "temporary", "start": "2025-06-22T00:00", "end": "2025-08-22T00:00", "isForwarded": false, "replacement": [ { "@type": "Replacement", "description": "Project A", "replacedBy": { "@type": "http://schema.org/Person", "name": "John Doe", "email": "john@doe.com", "phone": "+1234567890" } }, { "@type": "Replacement", "description": "Project B", "availabilityPattern": "Mo,Tu 12:00-15:00", "availabilityTimezone": "Europe/London", "replacedBy": { "@type": "http://schema.org/Person", "name": "Jane Doe", "email": "jane@doe.com", "phone": "+9876543210" } } ], "note": "I am currently on vacation." }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "unavailabilityType": "temporary", "start": "2025-06-22T00:00", "end": "2025-08-22T00:00", "isForwarded": false, "replacement": [ { "@type": "Replacement", "replacedBy": { "@type": "http://schema.org/Physician", "name": "Dr. Alice", "email": "contact@alice.example.com", "phone": "+1234567890" } }, { "@type": "Replacement", "availabilityPattern": "Mo,Tu,We", "replacedBy": { "@type": "http://schema.org/Physician", "name": "Dr. Bob", "email": "contact@bob.example.com", "phone": "+9876543210" } } ], "note": "Our doctor's office is closed for holidays." }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "unavailabilityType": "moved", "isForwarded": false, "replacement": { "@type": "Replacement", "replacedBy": { "@type": "http://schema.org/Person", "email": "john@doe.com", } }, "note": "May email has changed" }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "unavailabilityType": "noreply", }¶
{ "@context": "https://sml.draft.iana.org", "@type": "UnavailabilityInformation", "unavailabilityType": "noreply", "replacement": { "@type": "Replacement", "replacedBy": { "@type": "http://schema.org/Organization", "name": "Customer support", "phone": "+9876543210" } } }¶
The following vCard X-Properties
are currently used by the [RC-SVN] implementation to store incoming structured vacation notice data of absentees in the address book of the communication partner. I.e., if an email message with a structured vacation notice is processed, the implementation will lookup the absentee in the communication partner's address book and store the absence information, if an address book entry was found.¶
While this is mostly for internal data management in [RC-SVN], standardizing the vCard properties could be useful from a data portability perspective.¶
Most X-Properties
directly map to the example OutOfOffice
JSON-LD snippet above, X-OOF-UPDATED
was added to store the receiving date of the email message which contained the structured vacation notice.¶
X-OOF-UPDATED:2023-10-01 X-OOF-START:2023-10-01 X-OOF-END:2023-11-01 X-OOF-IS-FORWARDED:false X-OOF-REPLACEMENT:Jane Doe,Marketing,jane.doe@corp.com,+1234567-89 X-OOF-REPLACEMENT:John Doe,Development,john.doe@corp.com,+1234567-99 X-OOF-NOTE:I am out of office please reach my replacement instead¶