lisp/gnus/pop3.el

   1 ;;; pop3.el --- Post Office Protocol (RFC 1460) interface
   2
   3 ;; Copyright (C) 1996-2011 Free Software Foundation, Inc.
   4
   5 ;; Author: Richard L. Pieri <ratinox@peorth.gweep.net>
   6 ;; Maintainer: FSF
   7 ;; Keywords: mail
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software: you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation, either version 3 of the License, or
  14 ;; (at your option) any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  23
  24 ;;; Commentary:
  25
  26 ;; Most of the standard Post Office Protocol version 3 (RFC 1460) commands
  27 ;; are implemented.  The LIST command has not been implemented due to lack
  28 ;; of actual usefulness.
  29 ;; The optional POP3 command TOP has not been implemented.
  30
  31 ;; This program was inspired by Kyle E. Jones's vm-pop program.
  32
  33 ;;; Code:
  34
  35 (eval-when-compile (require 'cl))
  36
  37 (eval-and-compile
  38   ;; In Emacs 24, `open-protocol-stream' is an autoloaded alias for
  39   ;; `make-network-stream'.
  40   (unless (fboundp 'open-protocol-stream)
  41     (require 'proto-stream)))
  42
  43 (require 'mail-utils)
  44 (defvar parse-time-months)
  45
  46 (defgroup pop3 nil
  47   "Post Office Protocol."
  48   :group 'mail
  49   :group 'mail-source)
  50
  51 (defcustom pop3-maildrop (or (user-login-name)
  52                              (getenv "LOGNAME")
  53                              (getenv "USER"))
  54   "*POP3 maildrop."
  55   :version "22.1" ;; Oort Gnus
  56   :type 'string
  57   :group 'pop3)
  58
  59 (defcustom pop3-mailhost (or (getenv "MAILHOST") ;; nil -> mismatch
  60                              "pop3")
  61   "*POP3 mailhost."
  62   :version "22.1" ;; Oort Gnus
  63   :type 'string
  64   :group 'pop3)
  65
  66 (defcustom pop3-port 110
  67   "*POP3 port."
  68   :version "22.1" ;; Oort Gnus
  69   :type 'number
  70   :group 'pop3)
  71
  72 (defcustom pop3-password-required t
  73   "*Non-nil if a password is required when connecting to POP server."
  74   :version "22.1" ;; Oort Gnus
  75   :type 'boolean
  76   :group 'pop3)
  77
  78 ;; Should this be customizable?
  79 (defvar pop3-password nil
  80   "*Password to use when connecting to POP server.")
  81
  82 (defcustom pop3-authentication-scheme 'pass
  83   "*POP3 authentication scheme.
  84 Defaults to `pass', for the standard USER/PASS authentication.  The other
  85 valid value is 'apop'."
  86   :type '(choice (const :tag "Normal user/password" pass)
  87                  (const :tag "APOP" apop))
  88   :version "22.1" ;; Oort Gnus
  89   :group 'pop3)
  90
  91 (defcustom pop3-stream-length 100
  92   "How many messages should be requested at one time.
  93 The lower the number, the more latency-sensitive the fetching
  94 will be.  If your pop3 server doesn't support streaming at all,
  95 set this to 1."
  96   :type 'number
  97   :version "24.1"
  98   :group 'pop3)
  99
 100 (defcustom pop3-leave-mail-on-server nil
 101   "*Non-nil if the mail is to be left on the POP server after fetching.
 102
 103 If `pop3-leave-mail-on-server' is non-nil the mail is to be left
 104 on the POP server after fetching.  Note that POP servers maintain
 105 no state information between sessions, so what the client
 106 believes is there and what is actually there may not match up.
 107 If they do not, then you may get duplicate mails or the whole
 108 thing can fall apart and leave you with a corrupt mailbox."
 109   ;; We can't use the UILD support from XEmacs mail-lib or cvs.m17n.org:
 110   ;; http://thread.gmane.org/v9lld8fml4.fsf@marauder.physik.uni-ulm.de
 111   ;; http://thread.gmane.org/b9yy8hzy9ej.fsf@jpl.org
 112   ;; Any volunteer to re-implement this?
 113   :version "22.1" ;; Oort Gnus
 114   :type 'boolean
 115   :group 'pop3)
 116
 117 (defvar pop3-timestamp nil
 118   "Timestamp returned when initially connected to the POP server.
 119 Used for APOP authentication.")
 120
 121 (defvar pop3-read-point nil)
 122 (defvar pop3-debug nil)
 123
 124 ;; Borrowed from nnheader-accept-process-output in nnheader.el.  See the
 125 ;; comments there for explanations about the values.
 126
 127 (eval-and-compile
 128   (if (and (fboundp 'nnheader-accept-process-output)
 129            (boundp 'nnheader-read-timeout))
 130       (defalias 'pop3-accept-process-output 'nnheader-accept-process-output)
 131     ;; Borrowed from `nnheader.el':
 132     (defvar pop3-read-timeout
 133       (if (string-match "windows-nt\\|os/2\\|cygwin"
 134                         (symbol-name system-type))
 135           1.0
 136         0.01)
 137       "How long pop3 should wait between checking for the end of output.
 138 Shorter values mean quicker response, but are more CPU intensive.")
 139     (defun pop3-accept-process-output (process)
 140       (accept-process-output
 141        process
 142        (truncate pop3-read-timeout)
 143        (truncate (* (- pop3-read-timeout
 144                        (truncate pop3-read-timeout))
 145                     1000))))))
 146
 147 ;;;###autoload
 148 (defun pop3-movemail (file)
 149   "Transfer contents of a maildrop to the specified FILE.
 150 Use streaming commands."
 151   (let* ((process (pop3-open-server pop3-mailhost pop3-port))
 152          message-count message-total-size)
 153     (pop3-logon process)
 154     (with-current-buffer (process-buffer process)
 155       (let ((size (pop3-stat process)))
 156         (setq message-count (car size)
 157               message-total-size (cadr size)))
 158       (when (> message-count 0)
 159         (pop3-send-streaming-command
 160          process "RETR" message-count message-total-size)
 161         (pop3-write-to-file file)
 162         (unless pop3-leave-mail-on-server
 163           (pop3-send-streaming-command
 164            process "DELE" message-count nil))))
 165     (pop3-quit process)
 166     t))
 167
 168 (defun pop3-send-streaming-command (process command count total-size)
 169   (erase-buffer)
 170   (let ((i 1))
 171     (while (>= count i)
 172       (process-send-string process (format "%s %d\r\n" command i))
 173       ;; Only do 100 messages at a time to avoid pipe stalls.
 174       (when (zerop (% i pop3-stream-length))
 175         (pop3-wait-for-messages process i total-size))
 176       (incf i)))
 177   (pop3-wait-for-messages process count total-size))
 178
 179 (defun pop3-wait-for-messages (process count total-size)
 180   (while (< (pop3-number-of-responses total-size) count)
 181     (when total-size
 182       (message "pop3 retrieved %dKB (%d%%)"
 183                (truncate (/ (buffer-size) 1000))
 184                (truncate (* (/ (* (buffer-size) 1.0)
 185                                total-size) 100))))
 186     (pop3-accept-process-output process)))
 187
 188 (defun pop3-write-to-file (file)
 189   (let ((pop-buffer (current-buffer))
 190         (start (point-min))
 191         beg end
 192         temp-buffer)
 193     (with-temp-buffer
 194       (setq temp-buffer (current-buffer))
 195       (with-current-buffer pop-buffer
 196         (goto-char (point-min))
 197         (while (re-search-forward "^\\+OK" nil t)
 198           (forward-line 1)
 199           (setq beg (point))
 200           (when (re-search-forward "^\\.\r?\n" nil t)
 201             (setq start (point))
 202             (forward-line -1)
 203             (setq end (point)))
 204           (with-current-buffer temp-buffer
 205             (goto-char (point-max))
 206             (let ((hstart (point)))
 207               (insert-buffer-substring pop-buffer beg end)
 208               (pop3-clean-region hstart (point))
 209               (goto-char (point-max))
 210               (pop3-munge-message-separator hstart (point))
 211               (goto-char (point-max))))))
 212       (let ((coding-system-for-write 'binary))
 213         (goto-char (point-min))
 214         ;; Check whether something inserted a newline at the start and
 215         ;; delete it.
 216         (when (eolp)
 217           (delete-char 1))
 218         (write-region (point-min) (point-max) file nil 'nomesg)))))
 219
 220 (defun pop3-number-of-responses (endp)
 221   (let ((responses 0))
 222     (save-excursion
 223       (goto-char (point-min))
 224       (while (or (and (re-search-forward "^\\+OK" nil t)
 225                       (or (not endp)
 226                           (re-search-forward "^\\.\r?\n" nil t)))
 227                  (re-search-forward "^-ERR " nil t))
 228         (incf responses)))
 229     responses))
 230
 231 (defun pop3-logon (process)
 232   (let ((pop3-password pop3-password))
 233     ;; for debugging only
 234     (if pop3-debug (switch-to-buffer (process-buffer process)))
 235     ;; query for password
 236     (if (and pop3-password-required (not pop3-password))
 237         (setq pop3-password
 238               (read-passwd (format "Password for %s: " pop3-maildrop))))
 239     (cond ((equal 'apop pop3-authentication-scheme)
 240            (pop3-apop process pop3-maildrop))
 241           ((equal 'pass pop3-authentication-scheme)
 242            (pop3-user process pop3-maildrop)
 243            (pop3-pass process))
 244           (t (error "Invalid POP3 authentication scheme")))))
 245
 246 (defun pop3-get-message-count ()
 247   "Return the number of messages in the maildrop."
 248   (let* ((process (pop3-open-server pop3-mailhost pop3-port))
 249          message-count
 250          (pop3-password pop3-password))
 251     ;; for debugging only
 252     (if pop3-debug (switch-to-buffer (process-buffer process)))
 253     ;; query for password
 254     (if (and pop3-password-required (not pop3-password))
 255         (setq pop3-password
 256               (read-passwd (format "Password for %s: " pop3-maildrop))))
 257     (cond ((equal 'apop pop3-authentication-scheme)
 258            (pop3-apop process pop3-maildrop))
 259           ((equal 'pass pop3-authentication-scheme)
 260            (pop3-user process pop3-maildrop)
 261            (pop3-pass process))
 262           (t (error "Invalid POP3 authentication scheme")))
 263     (setq message-count (car (pop3-stat process)))
 264     (pop3-quit process)
 265     message-count))
 266
 267 (defcustom pop3-stream-type nil
 268   "*Transport security type for POP3 connexions.
 269 This may be either nil (plain connexion), `ssl' (use an
 270 SSL/TSL-secured stream) or `starttls' (use the starttls mechanism
 271 to turn on TLS security after opening the stream).  However, if
 272 this is nil, `ssl' is assumed for connexions to port
 273 995 (pop3s)."
 274   :version "23.1" ;; No Gnus
 275   :group 'pop3
 276   :type '(choice (const :tag "Plain" nil)
 277                  (const :tag "SSL/TLS" ssl)
 278                  (const starttls)))
 279
 280 (eval-and-compile
 281   (if (fboundp 'set-process-query-on-exit-flag)
 282       (defalias 'pop3-set-process-query-on-exit-flag
 283         'set-process-query-on-exit-flag)
 284     (defalias 'pop3-set-process-query-on-exit-flag
 285       'process-kill-without-query)))
 286
 287 (defun pop3-open-server (mailhost port)
 288   "Open TCP connection to MAILHOST on PORT.
 289 Returns the process associated with the connection."
 290   (let ((coding-system-for-read 'binary)
 291         (coding-system-for-write 'binary)
 292         result)
 293     (with-current-buffer
 294         (get-buffer-create (concat " trace of POP session to "
 295                                    mailhost))
 296       (erase-buffer)
 297       (setq pop3-read-point (point-min))
 298       (setq result
 299             (open-protocol-stream
 300              "POP" (current-buffer) mailhost port
 301              :type (cond
 302                     ((or (eq pop3-stream-type 'ssl)
 303                          (and (not pop3-stream-type)
 304                               (member port '(995 "pop3s"))))
 305                      'tls)
 306                     (t
 307                      (or pop3-stream-type 'network)))
 308              :capability-command "CAPA\r\n"
 309              :end-of-command "^\\.\r?\n\\|^\\(-ERR\\|+OK \\).*\n"
 310              :success "^\\+OK.*\n"
 311              :return-list t
 312              :starttls-function
 313              (lambda (capabilities)
 314                (and (string-match "\\bSTLS\\b" capabilities)
 315                     "STLS\r\n"))))
 316       (when result
 317         (let ((response (plist-get (cdr result) :greeting)))
 318           (setq pop3-timestamp
 319                 (substring response (or (string-match "<" response) 0)
 320                            (+ 1 (or (string-match ">" response) -1)))))
 321         (pop3-set-process-query-on-exit-flag (car result) nil)
 322         (erase-buffer)
 323         (car result)))))
 324
 325 ;; Support functions
 326
 327 (defun pop3-send-command (process command)
 328   (set-buffer (process-buffer process))
 329   (goto-char (point-max))
 330   ;; (if (= (aref command 0) ?P)
 331   ;;     (insert "PASS <omitted>\r\n")
 332   ;;   (insert command "\r\n"))
 333   (setq pop3-read-point (point))
 334   (goto-char (point-max))
 335   (process-send-string process (concat command "\r\n")))
 336
 337 (defun pop3-read-response (process &optional return)
 338   "Read the response from the server.
 339 Return the response string if optional second argument is non-nil."
 340   (let ((case-fold-search nil)
 341         match-end)
 342     (with-current-buffer (process-buffer process)
 343       (goto-char pop3-read-point)
 344       (while (and (memq (process-status process) '(open run))
 345                   (not (search-forward "\r\n" nil t)))
 346         (pop3-accept-process-output process)
 347         (goto-char pop3-read-point))
 348       (setq match-end (point))
 349       (goto-char pop3-read-point)
 350       (if (looking-at "-ERR")
 351           (error "%s" (buffer-substring (point) (- match-end 2)))
 352         (if (not (looking-at "+OK"))
 353             (progn (setq pop3-read-point match-end) nil)
 354           (setq pop3-read-point match-end)
 355           (if return
 356               (buffer-substring (point) match-end)
 357             t)
 358           )))))
 359
 360 (defun pop3-clean-region (start end)
 361   (setq end (set-marker (make-marker) end))
 362   (save-excursion
 363     (goto-char start)
 364     (while (and (< (point) end) (search-forward "\r\n" end t))
 365       (replace-match "\n" t t))
 366     (goto-char start)
 367     (while (and (< (point) end) (re-search-forward "^\\." end t))
 368       (replace-match "" t t)
 369       (forward-char)))
 370   (set-marker end nil))
 371
 372 ;; Copied from message-make-date.
 373 (defun pop3-make-date (&optional now)
 374   "Make a valid date header.
 375 If NOW, use that time instead."
 376   (require 'parse-time)
 377   (let* ((now (or now (current-time)))
 378          (zone (nth 8 (decode-time now)))
 379          (sign "+"))
 380     (when (< zone 0)
 381       (setq sign "-")
 382       (setq zone (- zone)))
 383     (concat
 384      (format-time-string "%d" now)
 385      ;; The month name of the %b spec is locale-specific.  Pfff.
 386      (format " %s "
 387              (capitalize (car (rassoc (nth 4 (decode-time now))
 388                                       parse-time-months))))
 389      (format-time-string "%Y %H:%M:%S " now)
 390      ;; We do all of this because XEmacs doesn't have the %z spec.
 391      (format "%s%02d%02d" sign (/ zone 3600) (/ (% zone 3600) 60)))))
 392
 393 (defun pop3-munge-message-separator (start end)
 394   "Check to see if a message separator exists.  If not, generate one."
 395   (save-excursion
 396     (save-restriction
 397       (narrow-to-region start end)
 398       (goto-char (point-min))
 399       (if (not (or (looking-at "From .?") ; Unix mail
 400                    (looking-at "\001\001\001\001\n") ; MMDF
 401                    (looking-at "BABYL OPTIONS:") ; Babyl
 402                    ))
 403           (let* ((from (mail-strip-quoted-names (mail-fetch-field "From")))
 404                  (tdate (mail-fetch-field "Date"))
 405                  (date (split-string (or (and tdate
 406                                               (not (string= "" tdate))
 407                                               tdate)
 408                                          (pop3-make-date))
 409                                      " "))
 410                  (From_))
 411             ;; sample date formats I have seen
 412             ;; Date: Tue, 9 Jul 1996 09:04:21 -0400 (EDT)
 413             ;; Date: 08 Jul 1996 23:22:24 -0400
 414             ;; should be
 415             ;; Tue Jul 9 09:04:21 1996
 416
 417             ;; Fixme: This should use timezone on the date field contents.
 418             (setq date
 419                   (cond ((not date)
 420                          "Tue Jan 1 00:00:0 1900")
 421                         ((string-match "[A-Z]" (nth 0 date))
 422                          (format "%s %s %s %s %s"
 423                                  (nth 0 date) (nth 2 date) (nth 1 date)
 424                                  (nth 4 date) (nth 3 date)))
 425                         (t
 426                          ;; this really needs to be better but I don't feel
 427                          ;; like writing a date to day converter.
 428                          (format "Sun %s %s %s %s"
 429                                  (nth 1 date) (nth 0 date)
 430                                  (nth 3 date) (nth 2 date)))
 431                         ))
 432             (setq From_ (format "\nFrom %s  %s\n" from date))
 433             (while (string-match "," From_)
 434               (setq From_ (concat (substring From_ 0 (match-beginning 0))
 435                                   (substring From_ (match-end 0)))))
 436             (goto-char (point-min))
 437             (insert From_)
 438             (if (search-forward "\n\n" nil t)
 439                 nil
 440               (goto-char (point-max))
 441               (insert "\n"))
 442             (let ((size (- (point-max) (point))))
 443               (forward-line -1)
 444               (insert (format "Content-Length: %s\n" size)))
 445             )))))
 446
 447 ;; The Command Set
 448
 449 ;; AUTHORIZATION STATE
 450
 451 (defun pop3-user (process user)
 452   "Send USER information to POP3 server."
 453   (pop3-send-command process (format "USER %s" user))
 454   (let ((response (pop3-read-response process t)))
 455     (if (not (and response (string-match "+OK" response)))
 456         (error "USER %s not valid" user))))
 457
 458 (defun pop3-pass (process)
 459   "Send authentication information to the server."
 460   (pop3-send-command process (format "PASS %s" pop3-password))
 461   (let ((response (pop3-read-response process t)))
 462     (if (not (and response (string-match "+OK" response)))
 463         (pop3-quit process))))
 464
 465 (defun pop3-apop (process user)
 466   "Send alternate authentication information to the server."
 467   (let ((pass pop3-password))
 468     (if (and pop3-password-required (not pass))
 469         (setq pass
 470               (read-passwd (format "Password for %s: " pop3-maildrop))))
 471     (if pass
 472         (let ((hash (md5 (concat pop3-timestamp pass) nil nil 'binary)))
 473           (pop3-send-command process (format "APOP %s %s" user hash))
 474           (let ((response (pop3-read-response process t)))
 475             (if (not (and response (string-match "+OK" response)))
 476                 (pop3-quit process)))))
 477     ))
 478
 479 ;; TRANSACTION STATE
 480
 481 (defun pop3-stat (process)
 482   "Return the number of messages in the maildrop and the maildrop's size."
 483   (pop3-send-command process "STAT")
 484   (let ((response (pop3-read-response process t)))
 485     (list (string-to-number (nth 1 (split-string response " ")))
 486           (string-to-number (nth 2 (split-string response " "))))
 487     ))
 488
 489 (defun pop3-list (process &optional msg)
 490   "If MSG is nil, return an alist of (MESSAGE-ID . SIZE) pairs.
 491 Otherwise, return the size of the message-id MSG"
 492   (pop3-send-command process (if msg
 493                                  (format "LIST %d" msg)
 494                                "LIST"))
 495   (let ((response (pop3-read-response process t)))
 496     (if msg
 497         (string-to-number (nth 2 (split-string response " ")))
 498       (let ((start pop3-read-point) end)
 499         (with-current-buffer (process-buffer process)
 500           (while (not (re-search-forward "^\\.\r\n" nil t))
 501             (pop3-accept-process-output process)
 502             (goto-char start))
 503           (setq pop3-read-point (point-marker))
 504           (goto-char (match-beginning 0))
 505           (setq end (point-marker))
 506           (mapcar #'(lambda (s) (let ((split (split-string s " ")))
 507                                   (cons (string-to-number (nth 0 split))
 508                                         (string-to-number (nth 1 split)))))
 509                   (split-string (buffer-substring start end) "\r\n" t)))))))
 510
 511 (defun pop3-retr (process msg crashbuf)
 512   "Retrieve message-id MSG to buffer CRASHBUF."
 513   (pop3-send-command process (format "RETR %s" msg))
 514   (pop3-read-response process)
 515   (let ((start pop3-read-point) end)
 516     (with-current-buffer (process-buffer process)
 517       (while (not (re-search-forward "^\\.\r\n" nil t))
 518         (unless (memq (process-status process) '(open run))
 519           (error "pop3 server closed the connection"))
 520         (pop3-accept-process-output process)
 521         (goto-char start))
 522       (setq pop3-read-point (point-marker))
 523       ;; this code does not seem to work for some POP servers...
 524       ;; and I cannot figure out why not.
 525       ;;      (goto-char (match-beginning 0))
 526       ;;      (backward-char 2)
 527       ;;      (if (not (looking-at "\r\n"))
 528       ;;          (insert "\r\n"))
 529       ;;      (re-search-forward "\\.\r\n")
 530       (goto-char (match-beginning 0))
 531       (setq end (point-marker))
 532       (pop3-clean-region start end)
 533       (pop3-munge-message-separator start end)
 534       (with-current-buffer crashbuf
 535         (erase-buffer))
 536       (copy-to-buffer crashbuf start end)
 537       (delete-region start end)
 538       )))
 539
 540 (defun pop3-dele (process msg)
 541   "Mark message-id MSG as deleted."
 542   (pop3-send-command process (format "DELE %s" msg))
 543   (pop3-read-response process))
 544
 545 (defun pop3-noop (process msg)
 546   "No-operation."
 547   (pop3-send-command process "NOOP")
 548   (pop3-read-response process))
 549
 550 (defun pop3-last (process)
 551   "Return highest accessed message-id number for the session."
 552   (pop3-send-command process "LAST")
 553   (let ((response (pop3-read-response process t)))
 554     (string-to-number (nth 1 (split-string response " ")))
 555     ))
 556
 557 (defun pop3-rset (process)
 558   "Remove all delete marks from current maildrop."
 559   (pop3-send-command process "RSET")
 560   (pop3-read-response process))
 561
 562 ;; UPDATE
 563
 564 (defun pop3-quit (process)
 565   "Close connection to POP3 server.
 566 Tell server to remove all messages marked as deleted, unlock the maildrop,
 567 and close the connection."
 568   (pop3-send-command process "QUIT")
 569   (pop3-read-response process t)
 570   (if process
 571       (with-current-buffer (process-buffer process)
 572         (goto-char (point-max))
 573         (delete-process process))))
 574 \f
 575 ;; Summary of POP3 (Post Office Protocol version 3) commands and responses
 576
 577 ;;; AUTHORIZATION STATE
 578
 579 ;; Initial TCP connection
 580 ;; Arguments: none
 581 ;; Restrictions: none
 582 ;; Possible responses:
 583 ;;  +OK [POP3 server ready]
 584
 585 ;; USER name
 586 ;; Arguments: a server specific user-id (required)
 587 ;; Restrictions: authorization state [after unsuccessful USER or PASS
 588 ;; Possible responses:
 589 ;;  +OK [valid user-id]
 590 ;;  -ERR [invalid user-id]
 591
 592 ;; PASS string
 593 ;; Arguments: a server/user-id specific password (required)
 594 ;; Restrictions: authorization state, after successful USER
 595 ;; Possible responses:
 596 ;;  +OK [maildrop locked and ready]
 597 ;;  -ERR [invalid password]
 598 ;;  -ERR [unable to lock maildrop]
 599
 600 ;; STLS      (RFC 2595)
 601 ;; Arguments: none
 602 ;; Restrictions: Only permitted in AUTHORIZATION state.
 603 ;; Possible responses:
 604 ;;  +OK
 605 ;;  -ERR
 606
 607 ;;; TRANSACTION STATE
 608
 609 ;; STAT
 610 ;; Arguments: none
 611 ;; Restrictions: transaction state
 612 ;; Possible responses:
 613 ;;  +OK nn mm [# of messages, size of maildrop]
 614
 615 ;; LIST [msg]
 616 ;; Arguments: a message-id (optional)
 617 ;; Restrictions: transaction state; msg must not be deleted
 618 ;; Possible responses:
 619 ;;  +OK [scan listing follows]
 620 ;;  -ERR [no such message]
 621
 622 ;; RETR msg
 623 ;; Arguments: a message-id (required)
 624 ;; Restrictions: transaction state; msg must not be deleted
 625 ;; Possible responses:
 626 ;;  +OK [message contents follow]
 627 ;;  -ERR [no such message]
 628
 629 ;; DELE msg
 630 ;; Arguments: a message-id (required)
 631 ;; Restrictions: transaction state; msg must not be deleted
 632 ;; Possible responses:
 633 ;;  +OK [message deleted]
 634 ;;  -ERR [no such message]
 635
 636 ;; NOOP
 637 ;; Arguments: none
 638 ;; Restrictions: transaction state
 639 ;; Possible responses:
 640 ;;  +OK
 641
 642 ;; LAST
 643 ;; Arguments: none
 644 ;; Restrictions: transaction state
 645 ;; Possible responses:
 646 ;;  +OK nn [highest numbered message accessed]
 647
 648 ;; RSET
 649 ;; Arguments: none
 650 ;; Restrictions: transaction state
 651 ;; Possible responses:
 652 ;;  +OK [all delete marks removed]
 653
 654 ;;; UPDATE STATE
 655
 656 ;; QUIT
 657 ;; Arguments: none
 658 ;; Restrictions: none
 659 ;; Possible responses:
 660 ;;  +OK [TCP connection closed]
 661
 662 (provide 'pop3)
 663
 664 ;;; pop3.el ends here