diff --git a/mailpile/config/defaults.py b/mailpile/config/defaults.py
index 8de28a1..e4e54a1 100644
--- a/mailpile/config/defaults.py
+++ b/mailpile/config/defaults.py
@@ -154,6 +154,7 @@ CONFIG_RULES = {
         'rescan_command':  (_('Command run before rescanning'), str,       ''),
         'default_email':   (_('Default outgoing e-mail address'), 'email', ''),
         'default_route':   (_('Default outgoing mail route'), str, ''),
+        'msgid_domain':    (_('Default outgoing message-id domain'), str, 'mailpile'),
         'line_length':     (_('Target line length, <40 disables reflow'),
                             int, 65),
         'always_bcc_self': (_('Always BCC self on outgoing mail'), bool, True),
diff --git a/mailpile/mailutils/emails.py b/mailpile/mailutils/emails.py
index 379781e..cb773d0 100644
--- a/mailpile/mailutils/emails.py
+++ b/mailpile/mailutils/emails.py
@@ -58,12 +58,15 @@ def MakeBoundary():
     return '==%s==' % okay_random(30)


-def MakeMessageID():
+def MakeMessageID(config):
     # We generate a message-ID which is almost entirely random; we
     # include an element of the local time (give-or-take 36 hours)
     # to further reduce the odds of any collision.
-    return '<%s%x@mailpile>' % (
-        okay_random(40), time.time() // (3600*48))
+
+    domain = config.prefs.get('msgid_domain') or 'mailpile'
+
+    return '<%s%x@%s>' % (
+        okay_random(40), time.time() // (3600*48), domain)


 def MakeMessageDate(ts=None):
@@ -407,7 +410,7 @@ class Email(object):
             msg['From'] = cls.encoded_hdr(None, 'from', value=msg_from)

         msg['Date'] = MakeMessageDate(msg_ts)
-        msg['Message-Id'] = msg_id or MakeMessageID()
+        msg['Message-Id'] = msg_id or MakeMessageID(idx.config)
         msg_subj = (msg_subject or '')
         msg['Subject'] = cls.encoded_hdr(None, 'subject', value=msg_subj)

diff --git a/mailpile/plugins/compose.py b/mailpile/plugins/compose.py
index 95cd53d..45fab14 100644
--- a/mailpile/plugins/compose.py
+++ b/mailpile/plugins/compose.py
@@ -113,7 +113,7 @@ def AddComposeMethods(cls):
             etype, etarg, msgid = msgid.split('-', 2)
             if etarg not in ('all', 'att'):
                 msgid = etarg + '-' + msgid
-            msgid = '<%s>' % msgid.replace('_', '@')
+            msgid = '<%s>' % self._deesc_msgid(msgid)
             etype = etype.lower()

             enc_msgid = idx._encode_msg_id(msgid)
@@ -142,6 +142,24 @@ def AddComposeMethods(cls):

             return Email(idx, e.msg_idx_pos)

+        def _new_msgid(self):
+            return MakeMessageID(self.session.config)
+
+        @classmethod
+        # Make a Message-ID safe for CSS/JS, escape @ and .,
+        # and also _ so we can use as an escape character
+        def _esc_msgid(cls, msgid):
+            return (msgid.replace('_', '_0')
+                    .replace('@', '_1')
+                    .replace('.', '_2'))
+
+        @classmethod
+        # Un-escape a Message-ID
+        def _deesc_msgid(cls, msgid):
+            return (msgid.replace('_2', '.')
+                    .replace('_1', '@')
+                    .replace('_0', '_'))
+
     return newcls


@@ -164,11 +182,6 @@ class CompositionCommand(AddComposeMethods(Search)):
     UPDATE_HEADERS = ('Subject', 'From', 'To', 'Cc', 'Bcc', 'Encryption',
                       'Attach-PGP-Pubkey')

-    def _new_msgid(self):
-        msgid = (MakeMessageID()
-                 .replace('.', '-')   # Dots may bother JS/CSS
-                 .replace('_', '-'))  # We use _ to encode the @ later on
-        return msgid

     def _get_email_updates(self, idx, create=False, noneok=False, emails=None):
         # Split the argument list into files and message IDs
@@ -337,7 +350,7 @@ class Compose(CompositionCommand):
             local_id, lmbox = session.config.open_local_mailbox(session)
         else:
             local_id, lmbox = -1, None
-            ephemeral = ['new-E-%s-mail' % msgid[1:-1].replace('@', '_')]
+            ephemeral = ['new-E-%s-mail' % cls._esc_msgid(msgid[1:-1])]
         profiles = session.config.vcards.find_vcards([], kinds=['profile'])
         return (Email.Create(idx, local_id, lmbox,
                              save=(not ephemeral),
@@ -509,7 +522,7 @@ class Reply(RelativeCompose):
         else:
             local_id, lmbox = -1, None
             fmt = 'reply-all-%s-%s' if reply_all else 'reply-%s-%s'
-            ephemeral = [fmt % (msgid[1:-1].replace('@', '_'),
+            ephemeral = [fmt % (cls._esc_msgid(msgid[1:-1]),
                                 refs[0].msg_mid())]

         if 'cc' in headers:
@@ -635,7 +648,7 @@ class Forward(RelativeCompose):
         else:
             local_id, lmbox = -1, None
             fmt = 'forward-att-%s-%s' if msg_atts else 'forward-%s-%s'
-            ephemeral = [fmt % (msgid[1:-1].replace('@', '_'),
+            ephemeral = [fmt % (cls._esc_msgid(msgid[1:-1]),
                                 refs[0].msg_mid())]

         if cid: