1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501
|
<pre>Internet Engineering Task Force (IETF) J. Levine
Request for Comments: 6783 Taughannock Networks
Obsoletes: <a href="./rfc5983">5983</a> R. Gellens
Category: Informational Qualcomm Incorporated
ISSN: 2070-1721 November 2012
<span class="h1">Mailing Lists and Non-ASCII Addresses</span>
Abstract
This document describes considerations for mailing lists with the
introduction of non-ASCII UTF-8 email addresses. It outlines some
possible scenarios for handling lists with mixtures of non-ASCII and
traditional addresses but does not specify protocol changes or offer
implementation or deployment advice.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
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). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see <a href="./rfc5741#section-2">Section 2 of RFC 5741</a>.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
<a href="http://www.rfc-editor.org/info/rfc6783">http://www.rfc-editor.org/info/rfc6783</a>.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and the IETF Trust's Legal
Provisions Relating to IETF Documents
(<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to 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 are provided without warranty as
described in the Simplified BSD License.
<span class="grey">Levine & Gellens Informational [Page 1]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-2" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
Table of Contents
<a href="#section-1">1</a>. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-2">2</a>
<a href="#section-1.1">1.1</a>. Mailing List Header Additions and Modifications . . . . . . <a href="#page-3">3</a>
<a href="#section-1.2">1.2</a>. Non-ASCII Email Addresses . . . . . . . . . . . . . . . . . <a href="#page-3">3</a>
<a href="#section-2">2</a>. Scenarios Involving Mailing Lists . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-2.1">2.1</a>. Fully SMTPUTF8 Lists . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-2.2">2.2</a>. Mixed SMTPUTF8 and ASCII Lists . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-2.3">2.3</a>. SMTP Issues . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-3">3</a>. List Headers . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-6">6</a>
<a href="#section-3.1">3.1</a>. SMTPUTF8 List Headers . . . . . . . . . . . . . . . . . . . <a href="#page-6">6</a>
<a href="#section-3.2">3.2</a>. Downgrading List Headers . . . . . . . . . . . . . . . . . <a href="#page-7">7</a>
<a href="#section-3.3">3.3</a>. Subscribers' Addresses in Downgraded Headers . . . . . . . <a href="#page-8">8</a>
<a href="#section-4">4</a>. Security Considerations . . . . . . . . . . . . . . . . . . . . <a href="#page-8">8</a>
<a href="#section-5">5</a>. References . . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-8">8</a>
<a href="#section-5.1">5.1</a>. Normative References . . . . . . . . . . . . . . . . . . . <a href="#page-8">8</a>
<a href="#section-5.2">5.2</a>. Informative References . . . . . . . . . . . . . . . . . . <a href="#page-9">9</a>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
This document describes considerations for mailing lists with the
introduction of non-ASCII UTF-8 email addresses. The usage of such
addresses is described in [<a href="./rfc6530" title=""Overview and Framework for Internationalized Email"">RFC6530</a>].
Mailing lists are an important part of email usage and collaborative
communications. The introduction of internationalized email
addresses affects mailing lists in three main areas: (1) transport
(receiving and sending messages); (2) message headers of received and
retransmitted messages; and (3) mailing list operational policies.
A mailing list is a mechanism that distributes a message to multiple
recipients when the originator sends it to a single address. An
agent, usually software rather than a person, at that single address
receives the message and then causes the message to be redistributed
to a list of recipients. This agent usually sets the envelope return
address (henceforth called the "bounce address") of the redistributed
message to a different address from that of the original message.
Using a different bounce address directs error and other
automatically generated messages to an error-handling address
associated with the mailing list. This sends error and other
automatic messages to the list agent, which can often do something
useful with them, rather than to the original sender, who typically
doesn't control the list and hence can't do anything about them.
In most cases, the mailing list agent redistributes a received
message to its subscribers as a new message, that is, conceptually it
uses message submission [<a href="./rfc6409" title=""Message Submission for Mail"">RFC6409</a>] (as did the sender of the original
message). The exception, where the mailing list is not managed by a
<span class="grey">Levine & Gellens Informational [Page 2]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-3" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
separate agent that receives and redistributes messages in separate
transactions but is implemented by an expansion step within an SMTP
transaction where one local address expands to multiple local or non-
local addresses, is not addressed by this document.
<span class="h3"><a class="selflink" id="section-1.1" href="#section-1.1">1.1</a>. Mailing List Header Additions and Modifications</span>
Some list agents alter message header fields, while others do not. A
number of standardized list-related header fields have been defined,
and many lists add one or more of these headers. Separate from these
standardized list-specific header fields, and despite a history of
interoperability problems from doing so, some lists alter or add
header fields in an attempt to control where replies are sent. Such
lists typically add or replace the "Reply-To" field, and some add or
replace the "Sender" field. Some lists alter or replace other
fields, including "From".
Among these list-specific header fields are those specified in RFCs
2369 [<a href="./rfc2369" title=""The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields"">RFC2369</a>] and 2919 [<a href="./rfc2919" title=""List-Id: A Structured Field and Namespace for the Identification of Mailing Lists"">RFC2919</a>]. For more information, see
<a href="#section-3">Section 3</a>.
<span class="h3"><a class="selflink" id="section-1.2" href="#section-1.2">1.2</a>. Non-ASCII Email Addresses</span>
While the mail transport protocol is the same for regular email
recipients and mailing list recipients, list agents have special
considerations with non-ASCII email addresses because they retransmit
messages composed by other agents to potentially many recipients.
There are considerations for non-ASCII email addresses in the
envelope as well as in header fields of redistributed messages. In
particular, a message with non-ASCII addresses in the headers or
envelope cannot be sent to non-SMTPUTF8 recipients.
With mailing lists, there are two different types of considerations:
first, the purely technical ones involving message handling, error
cases, and the like, and second, those that arise from the fact that
humans use mailing lists to communicate. As an example of the first,
list agents might choose to reject all messages from non-ASCII
addresses if they are unprepared to handle SMTPUTF8 mail. As an
example of the second, a user who sends a message to a list often is
unaware of the list membership. In particular, the user often
doesn't know if the members are SMTPUTF8 mail users or not, and often
neither the original sender nor the recipients personally know each
other. As a consequence of this, remedies that may be readily
available for one-to-one communication might not be appropriate when
dealing with mailing lists. For example, if a user sends a message
that is undeliverable, normally the telephone, instant messaging, or
other forms of communication are available to obtain a working
<span class="grey">Levine & Gellens Informational [Page 3]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-4" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
address. With mailing lists, the users may not have any recourse.
Of course, with mailing lists, the original sender usually does not
know which list members successfully received a message or if it was
undeliverable to some.
Conceptually, a mailing list's internationalization can be divided
into three capabilities. First, does the list have a non-ASCII
submission address? Second, does the list agent accept subscriptions
for addresses containing non-ASCII characters? And third, does the
list agent accept messages that require SMTPUTF8 capabilities?
If a list has subscribers with ASCII addresses, those subscribers
might or might not be able to accept SMTPUTF8 messages.
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Scenarios Involving Mailing Lists</span>
Generally (and exclusively within the scope of this document), an
original message is sent to a mailing list as a completely separate
and independent transaction from the list agent sending the
retransmitted message to one or more list recipients. In both cases,
the message might be addressed only to the list address or might have
recipients in addition to the list. Furthermore, the list agent
might choose to send the retransmitted message to each list recipient
in a separate message submission transaction or might choose to
include multiple recipients per transaction. Often, list agents are
constructed to work in cooperation with, rather than include the
functionality of, a message submission server; hence, the list
transmits to a single submission server one copy of the retransmitted
message. The submission server then decides which recipients to
include in which transaction.
<span class="h3"><a class="selflink" id="section-2.1" href="#section-2.1">2.1</a>. Fully SMTPUTF8 Lists</span>
Some lists may wish to be fully SMTPUTF8. That is, all subscribers
are expected to be able to receive SMTPUTF8 mail. For list hygiene
reasons, such a list would probably want to prevent subscriptions
from addresses that are unable to receive SMTPUTF8 mail. If a
putative subscriber has a non-ASCII address, it must be able to
receive SMTPUTF8 mail, but there is no way to tell whether a
subscriber with an ASCII address can receive SMTPUTF8 mail short of
sending an SMTPUTF8 probe or confirmation message and somehow finding
out whether it was delivered, e.g., if the user clicked a link in the
confirmation message.
<span class="grey">Levine & Gellens Informational [Page 4]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-5" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
<span class="h3"><a class="selflink" id="section-2.2" href="#section-2.2">2.2</a>. Mixed SMTPUTF8 and ASCII Lists</span>
Other lists may wish to handle a mixture of SMTPUTF8 and ASCII
subscribers, either as a transitional measure as subscribers upgrade
to SMTPUTF8-capable mail software or as an ongoing feature. While it
is not possible in general to downgrade SMTPUTF8 mail to ASCII mail,
list software might divide the recipients into two sets, SMTPUTF8 and
ASCII recipients, and create a downgraded version of SMTPUTF8 list
messages to send to ASCII recipients. See Sections <a href="#section-3.2">3.2</a> and <a href="#section-3.3">3.3</a>.
To determine which set an address belongs in, list software might
make the conservative assumption that ASCII addresses get ASCII
messages, it might try to probe the address with an SMTPUTF8 test
message, or it might let the subscriber set the message format
manually, similar to the way that some lists now let subscribers
choose between plain text and HTML mail, or individual messages and a
daily digest.
To determine whether a message needs to be downgraded for ASCII
recipients, list software might assume that any message received via
an SMTPUTF8 SMTP session is an SMTPUTF8 message or might examine the
headers and body of the message to see whether it needs SMTPUTF8
treatment. Depending on the interface between the list software and
the Mail Transfer Agent (MTA) and Mail Delivery Agent (MDA) that
handle incoming messages, it may not be able to tell the type of
session for incoming messages.
<span class="h3"><a class="selflink" id="section-2.3" href="#section-2.3">2.3</a>. SMTP Issues</span>
Mailing list software usually changes the envelope addresses on each
message. The bounce address is set to an address that will return
bounces to the list agent, and the recipient addresses are set to the
subscribers of the list. For some lists, all messages to a list get
the same bounce address. For others, list software may create a
bounce address per recipient or a unique bounce address per message
per recipient, bounce management techniques known as Variable
Envelope Return Paths or VERP [<a href="#ref-VERP" title=""Variable Envelope Return Paths"">VERP</a>].
The bounce address for a list typically includes the name of the
list, so a list with a non-ASCII name will have a non-ASCII bounce
address. Given the unknown paths that bounce messages might take,
list software might instead use an ASCII bounce address to make it
more likely that bounces can be delivered back to the list agent.
Similarly, a VERP address for each subscriber typically embeds a
version of the subscriber's address so the VERP bounce address for a
non-ASCII subscriber address will be a non-ASCII address. For the
same reason, the list software might use ASCII bounce addresses that
encode the recipient's identity in some other way.
<span class="grey">Levine & Gellens Informational [Page 5]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-6" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. List Headers</span>
List agents typically add list-specific headers to each message
before resending the message to list recipients.
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. SMTPUTF8 List Headers</span>
The list headers in RFCs 2369 [<a href="./rfc2369" title=""The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields"">RFC2369</a>] and 2919 [<a href="./rfc2919" title=""List-Id: A Structured Field and Namespace for the Identification of Mailing Lists"">RFC2919</a>] were all
specified before SMTPUTF8 mail existed, and their definitions do not
address where non-ASCII characters might appear. These include, for
example:
List-Id: List Header Mailing List
<list-header.example.com>
List-Help:
<mailto:list@example.com?subject=help>
List-Unsubscribe:
<mailto:list@example.com?subject=unsubscribe>
List-Subscribe:
<mailto:list@example.com?subject=subscribe>
List-Post:
<mailto:list@example.com>
List-Owner:
<mailto:listmom@example.com> (Contact Person for Help)
List-Archive:
<mailto:archive@example.com?subject=index%20list>
As described in [<a href="./rfc2369" title=""The Use of URLs as Meta-Syntax for Core Mail List Commands and their Transport through Message Header Fields"">RFC2369</a>], "[t]he contents of the list header fields
mostly consist of angle-bracket ('<', '>') enclosed URLs, with
internal whitespace being ignored". [<a href="./rfc2919" title=""List-Id: A Structured Field and Namespace for the Identification of Mailing Lists"">RFC2919</a>] specifies that "[t]he
list identifier will, in most cases, appear like a host name in a
domain of the list owner". Since these headers were defined in the
context of ASCII mail, these headers permit only ASCII text,
including in the URLs.
The most commonly used URI schemes in List-* headers tend to be http
and mailto [<a href="./rfc6068" title=""The 'mailto' URI Scheme"">RFC6068</a>], although they sometimes include https and ftp
and, in principle, can contain any valid URI.
Even if a scheme permits an internationalized form, it should use a
pure ASCII form of the URI described in [<a href="./rfc3986" title=""Uniform Resource Identifier (URI): Generic Syntax"">RFC3986</a>]. Future work may
extend these header fields or define replacements to directly support
unencoded non-ASCII outside the ASCII repertoire in these and other
header fields, but in the absence of such extension or replacement,
non-ASCII characters can only be included by encoding them as ASCII.
<span class="grey">Levine & Gellens Informational [Page 6]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-7" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
The encoding technique specified in [<a href="./rfc3986" title=""Uniform Resource Identifier (URI): Generic Syntax"">RFC3986</a>] is to use a pair of hex
digits preceded by a percent sign, but percent signs have been used
informally in mail addresses to do source routing. Although few mail
systems still permit source routing, a lot of mail software still
forbids or escapes characters formerly used for source routing, which
can lead to unfortunate interactions with percent-encoded URIs or any
URI that includes one of those characters. If a program interpreting
a mailto: URI knew that the Mail User Agent (MUA) in use were able to
handle non-ASCII data, the program could pass the URI in unencoded
non-ASCII, avoiding problems with misinterpreted percent signs, but
at this point, there is no standard or even informal way for MUAs to
signal SMTPUTF8 capabilities. Also, note that whether
internationalized domain names should be percent-encoded or appear in
A-label form [<a href="./rfc5890" title=""Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework"">RFC5890</a>] depends on the context in which they occur.
The List-ID header field uniquely identifies a list. The intent is
that the value of this header remain constant, even if the machine or
system used to operate or host the list changes. This header field
is often used in various filters and tests, such as client-side
filters, Sieve filters [<a href="./rfc5228" title=""Sieve: An Email Filtering Language"">RFC5228</a>], and so forth. If the definition of
a List-ID header field were to be extended to allow non-ASCII text,
filters and tests might not properly compare encoded and unencoded
versions of a non-ASCII value. In addition to these comparison
considerations, it is generally desirable that this header field
contain something meaningful that users can type in. However, ASCII
encodings of non-ASCII characters are unlikely to be meaningful to
users or easy for them to accurately type.
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. Downgrading List Headers</span>
If list software prepares a downgraded version of an SMTPUTF8
message, all the List-* headers must be downgraded. In particular,
if a List-* header contains a non-ASCII mailto (even encoded in
ASCII), it may be advisable to edit the header to remove the non-
ASCII address or replace it with an equivalent ASCII address if one
is known to the list software. Otherwise, a client might run into
trouble if the decoded mailto results in a non-ASCII address. If a
header that contains a mailto URL is downgraded by percent encoding,
some mail software may misinterpret the percent signs as attempted
source routing.
When downgrading list headers, it may not be possible to produce a
downgraded version that is satisfactorily equivalent to the original
header. In particular, if a non-ASCII List-ID is downgraded to an
ASCII version, software and humans at recipient systems will
typically not be able to tell that both refer to the same list.
<span class="grey">Levine & Gellens Informational [Page 7]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-8" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
If lists permit mail with multiple MIME parts, some MIME headers in
SMTPUTF8 messages may include non-ASCII characters in file names and
other descriptive text strings. Downgrading these strings may lose
the sense of the names, break references from other MIME parts (such
as HTML IMG references to embedded images), and otherwise damage the
mail.
<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a>. Subscribers' Addresses in Downgraded Headers</span>
List software typically leaves the original submitter's address in
the From: line, both so that recipients can tell who wrote the
message and so that they have a choice of responding to the list or
directly to the submitter. If a submitter has a non-ASCII address,
there is no way to downgrade the From: header and preserve the
address so that ASCII recipients can respond to it, since non-
SMTPUTF8 mail systems can't send mail to non-ASCII addresses.
Possible work-arounds (none implemented that we know of) might
include allowing subscribers with non-ASCII addresses to register an
alternate ASCII address with the list software, having the list
software itself create ASCII forwarding addresses, or just putting
the list's address in the From: line and losing the ability to
respond directly to the submitter.
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Security Considerations</span>
None beyond what mailing list agents do now.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. References</span>
<span class="h3"><a class="selflink" id="section-5.1" href="#section-5.1">5.1</a>. Normative References</span>
[<a id="ref-RFC3986">RFC3986</a>] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
<a href="./rfc3986">RFC 3986</a>, January 2005.
[<a id="ref-RFC6068">RFC6068</a>] Duerst, M., Masinter, L., and J. Zawinski, "The 'mailto'
URI Scheme", <a href="./rfc6068">RFC 6068</a>, October 2010.
[<a id="ref-RFC6409">RFC6409</a>] Gellens, R. and J. Klensin, "Message Submission for Mail",
STD 72, <a href="./rfc6409">RFC 6409</a>, November 2011.
[<a id="ref-RFC6530">RFC6530</a>] Klensin, J. and Y. Ko, "Overview and Framework for
Internationalized Email", <a href="./rfc6530">RFC 6530</a>, February 2012.
<span class="grey">Levine & Gellens Informational [Page 8]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-9" ></span>
<span class="grey"><a href="./rfc6783">RFC 6783</a> Mailing Lists and Non-ASCII Addresses November 2012</span>
<span class="h3"><a class="selflink" id="section-5.2" href="#section-5.2">5.2</a>. Informative References</span>
[<a id="ref-RFC2369">RFC2369</a>] Neufeld, G. and J. Baer, "The Use of URLs as Meta-Syntax
for Core Mail List Commands and their Transport through
Message Header Fields", <a href="./rfc2369">RFC 2369</a>, July 1998.
[<a id="ref-RFC2919">RFC2919</a>] Chandhok, R. and G. Wenger, "List-Id: A Structured Field
and Namespace for the Identification of Mailing Lists",
<a href="./rfc2919">RFC 2919</a>, March 2001.
[<a id="ref-RFC5228">RFC5228</a>] Guenther, P. and T. Showalter, "Sieve: An Email Filtering
Language", <a href="./rfc5228">RFC 5228</a>, January 2008.
[<a id="ref-RFC5890">RFC5890</a>] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework",
<a href="./rfc5890">RFC 5890</a>, August 2010.
[<a id="ref-VERP">VERP</a>] Bernstein, D., "Variable Envelope Return Paths",
February 1997, <<a href="http://cr.yp.to/proto/verp.txt">http://cr.yp.to/proto/verp.txt</a>>.
Authors' Addresses
John Levine
Taughannock Networks
PO Box 727
Trumansburg, NY 14886
US
Phone: +1 831 480 2300
EMail: standards@taugh.com
URI: <a href="http://jl.ly">http://jl.ly</a>
Randall Gellens
Qualcomm Incorporated
5775 Morehouse Drive
San Diego, CA 92121
US
EMail: rg+ietf@qti.qualcomm.com
Levine & Gellens Informational [Page 9]
</pre>
|