C: STORE 4 6-7 +FLAGS=DELETED
      S: * FETCH 4 FLAGS=SEEN,DELETED
      S: * FETCH 6 FLAGS=SEEN,DELETED
      S: * FETCH 7 FLAGS=SEEN,DELETED
      S: +OK STORE completed
      C: STORE 4 "INTERNALDATE=Mon, 20 Jan 2003 18:43:09 -0500"
      S: * FETCH 4 "INTERNALDATE=Mon, 20 Jan 2003 18:43:09 -0500"
      S: +OK STORE completed
The STORE command updates
    attributes of existing messages. A list of message numbers, as
    whitespace-delimited words, follows the STORE. “m-n”
    designates messages #m through #n, inclusively.
One or more words follow the message number list; they
    specify which attributes to set. Attribute settings are
    generally specified as name=value. As is with the
    FETCH command, servers should
    ignore attributes they do not recognize. The following
    attributes are defined at this time:
listSets the messages flags precisely to list, which is a
          comma-separated list of message flags. See “Reading message
          attributes” for a list of defined
          message flags.
listAdds the flags in list to the messages'
          flags. Other flags, if they are set for a message, remain
          set.
listRemove the flags in list from the messages'
          flags. Other flags, if they are set for a message, remain
          set.
listIf the server's capability list includes “KEYWORD”, then set
          the keywords associated with the message to list, which is a
          comma-separated list of keywords. See “SMAP connection
          negotiation” for more
          information.
listAdds keywords named in list, which is a
          comma-separated list of keywords, to the existing
          keywords already set for the message. Existing keywords
          remain unaffected.
listRemoves keywords named in list, which is a
          comma-separated list of keywords, from the list of
          existing keywords associated with this message.
dateSet the INTERNALDATE
          timestamp on a message to date, which is an
          RFC-2822 formatted date/time value. See “Reading message
          attributes” for more information
          on the INTERNALDATE
          attribute.
The server's response includes “*
    FETCH” single line replies that give
    the updated attributes of all affected messages. This is
    specifically needed when updating message flags, and is
    optional when updating INTERNALDATEs (there's not much point in
    echoing back the same timestamp).