diff --git a/src/irclib.py b/src/irclib.py
index 9aa085d3b..80449a621 100644
--- a/src/irclib.py
+++ b/src/irclib.py
@@ -1218,6 +1218,15 @@ class Irc(IrcCommandDispatcher, log.Firewalled):
         self.state = IrcState()
         self.queue = IrcMsgQueue()
         self.fastqueue = smallqueue()
+
+        # Messages of batches that are currently in one self.queue (not
+        # self.fastqueue).
+        # This works by adding only the first message of a batch in a queue,
+        # and when self.takeMsg pops that message from the queue, it will
+        # also pop the whole batch from self._queued_batches and atomically
+        # add it to self.fastqueue
+        self._queued_batches = {}
+
         self.driver = None # The driver should set this later.
         self._setNonResettingVariables()
         self._queueConnectMessages()
@@ -1306,6 +1315,9 @@ class Irc(IrcCommandDispatcher, log.Firewalled):
 
     def queueMsg(self, msg):
         """Queues a message to be sent to the server."""
+        if msg.command.upper() == 'BATCH':
+            log.error('Tried to send a BATCH message using queueMsg '
+                      'instead of queueBatch: %r', msg)
         if not self.zombie:
             return self.queue.enqueue(msg)
         else:
@@ -1314,11 +1326,60 @@ class Irc(IrcCommandDispatcher, log.Firewalled):
 
     def sendMsg(self, msg):
         """Queues a message to be sent to the server *immediately*"""
+        if msg.command.upper() == 'BATCH':
+            log.error('Tried to send a BATCH message using sendMsg '
+                      'instead of queueBatch: %r', msg)
         if not self.zombie:
             self.fastqueue.enqueue(msg)
         else:
             log.warning('Refusing to send %r; %s is a zombie.', msg, self)
 
+    def queueBatch(self, msgs):
+        """Queues a batch of messages to be sent to the server.
+        See <https://ircv3.net/specs/extensions/batch-3.2>
+
+        queueMsg/sendMsg must not be used repeatedly to send a batch, because
+        they do not guarantee the batch is send atomically, which is
+        required because "Clients MUST NOT send messages other than PRIVMSG
+        while a multiline batch is open."
+        -- <https://ircv3.net/specs/extensions/multiline>
+        """
+        if not conf.supybot.protocols.irc.experimentalExtensions():
+            log.error('queueBatch is disabled because it depends on draft '
+                      'IRC specifications. If you know what you are doing, '
+                      'set supybot.protocols.irc.experimentalExtensions.')
+            return
+        if len(msg) < 2:
+            log.error('queueBatch called with less than two messages.')
+            return
+        if msgs[0].command.upper() != 'BATCH' or msgs[0].args[0][0] != '+':
+            log.error('queueBatch called with non-"BATCH +" as first message.')
+            return
+        if msgs[-1].command.upper() != 'BATCH' or msgs[-1].args[0][0] != '-':
+            log.error('queueBatch called with non-"BATCH -" as last message.')
+            return
+        batch_name = msgs[0].args[0][1:]
+        if msgs[0].args[0][1:] != batch_name:
+            log.error('queueBatch called with mismatched BATCH name args.')
+            return
+        if any(msg.server_tags.get('batch') != batch_name for msg in msgs):
+            log.error('queueBatch called with mismatched batch names.')
+            return
+        if batch_name in self._queued_batches:
+            log.error('queueBatch called with a batch name already in flight')
+            return
+        self._queued_batches[batch_name] = msgs
+
+        # Enqueue only the start of the batch. When takeMsg sees it, it will
+        # enqueue the full batch in self.fastqueue.
+        # We don't enqueue the full batch in self.fastqueue here, because
+        # there is no reason for this batch to jump in front of all other
+        # queued messages.
+        # TODO: the batch will be ordered with the priority of a BATCH
+        # message (ie. normal), but if the batch is made only of low-priority
+        # messages like PRIVMSG, it should have that priority.
+        self.queue.enqueue(msgs[0])
+
     def _truncateMsg(self, msg):
         msg_str = str(msg)
         if msg_str[0] == '@':
@@ -1381,7 +1442,36 @@ class Irc(IrcCommandDispatcher, log.Firewalled):
                 now = str(int(now))
                 self.outstandingPing = True
                 self.queueMsg(ircmsgs.ping(now))
+
         if msg:
+            if msg.command.upper() == 'BATCH':
+                if not conf.supybot.protocols.irc.experimentalExtensions():
+                    log.error('Dropping outgoing batch.'
+                              'supybot.protocols.irc.experimentalExtensions'
+                              'is disabled, so plugins should not send '
+                              'batches. This is a bug, please report it.')
+                    return None
+                if msg.args[0].startswith('+'):
+                    # Start of a batch; created by self.queueBatch. We need to
+                    # add *prepend* the rest of the batch to the fastqueue
+                    # so that no other message is sent while the batch is
+                    # open.
+                    # "Clients MUST NOT send messages other than PRIVMSG while
+                    # a multiline batch is open."
+                    # -- <https://ircv3.net/specs/extensions/multiline>
+                    #
+                    # (Yes, *prepend* to the queue. Fortunately, it should be
+                    # empty, because BATCH cannot be queued in the fastqueue
+                    # and we just got a BATCH, which means it's from the
+                    # regular queue, which means the fastqueue is empty.
+                    # But let's not take any risk, eg. if race condition
+                    # with a plugin appending directly to the fastqueue.)
+                    batch_messages = self._queued_batches
+                    if batch_messages[0] != msg:
+                        log.error('Enqueue "BATCH +" message does not match '
+                                  'the one of the batch in flight.')
+                    self.fastqueue[:0] = batch_messages[1:]
+
             if not world.testing and 'label' not in msg.server_tags \
                     and 'labeled-response' in self.state.capabilities_ack:
                 # Not adding labels while testing, because it would break