diff --git a/mailman/Mailman/Defaults.py.in b/mailman/Mailman/Defaults.py.in

index 142f5d8..df10473 100644

--- a/mailman/Mailman/Defaults.py.in

+++ b/mailman/Mailman/Defaults.py.in

@@ -394,6 +394,7 @@ POSTFIX_STYLE_VIRTUAL_DOMAINS = []

 # separating space), so it must be appropriate for os.system().

 POSTFIX_ALIAS_CMD = '/usr/sbin/postalias'

 POSTFIX_MAP_CMD = '/usr/sbin/postmap'

+POSTFIX_CONF_CMD = '/usr/sbin/postconf'

 # Ceiling on the number of recipients that can be specified in a single SMTP

 # transaction.  Set to 0 to submit the entire recipient list in one

diff --git a/mailman/Mailman/MTA/Postfix.py b/mailman/Mailman/MTA/Postfix.py

index 33cb9a4..6161f58 100644

--- a/mailman/Mailman/MTA/Postfix.py

+++ b/mailman/Mailman/MTA/Postfix.py

@@ -45,19 +45,24 @@ except NameError:

 def _update_maps():

     msg = 'command failed: %s (status: %s, %s)'

-    acmd = mm_cfg.POSTFIX_ALIAS_CMD + ' ' + ALIASFILE

-    status = (os.system(acmd) >> 8) & 0xff

-    if status:

-        errstr = os.strerror(status)

-        syslog('error', msg, acmd, status, errstr)

-        raise RuntimeError, msg % (acmd, status, errstr)

-    if os.path.exists(VIRTFILE):

-        vcmd = mm_cfg.POSTFIX_MAP_CMD + ' ' + VIRTFILE

-        status = (os.system(vcmd) >> 8) & 0xff

-        if status:

-            errstr = os.strerror(status)

-            syslog('error', msg, vcmd, status, errstr)

-            raise RuntimeError, msg % (vcmd, status, errstr)

+    ccmd = mm_cfg.POSTFIX_CONF_CMD + ' -h alias_maps'

+    for mapfile in os.popen(ccmd).readline().rstrip('\n').split(','):

+	if mapfile == ALIASFILE or mapfile.endswith(':' + ALIASFILE):

+	    acmd = mm_cfg.POSTFIX_ALIAS_CMD + ' ' + mapfile

+	    status = (os.system(acmd) >> 8) & 0xff

+	    if status:

+		errstr = os.strerror(status)

+		syslog('error', msg, acmd, status, errstr)

+		raise RuntimeError, msg % (acmd, status, errstr)

+    ccmd = mm_cfg.POSTFIX_CONF_CMD + ' -h virtual_maps'

+    for mapfile in os.popen(ccmd).readline().rstrip('\n').split(','):

+	if (mapfile == VIRTFILE or mapfile.endswith(':' + VIRTFILE)) and os.path.exists(VIRTFILE):

+	    vcmd = mm_cfg.POSTFIX_MAP_CMD + ' ' + mapfile

+	    status = (os.system(vcmd) >> 8) & 0xff

+	    if status:

+		errstr = os.strerror(status)

+		syslog('error', msg, vcmd, status, errstr)

+		raise RuntimeError, msg % (vcmd, status, errstr)