diff --git a/CHANGELOG.md b/CHANGELOG.md
index a912f2b8..88552e5f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ In Development
 --------------
 
 * Roundcube updated to version 1.1.4.
+* On multi-homed machines, Postfix now binds to the right network interface when sending outbound mail so that SPF checks on the receiving end will pass.
 
 v0.16 (January 30, 2016)
 ------------------------
diff --git a/setup/mail-postfix.sh b/setup/mail-postfix.sh
index 6124d64e..bf211ca3 100755
--- a/setup/mail-postfix.sh
+++ b/setup/mail-postfix.sh
@@ -57,11 +57,14 @@ apt_install postfix postfix-pcre postgrey ca-certificates
 # Set some basic settings...
 #
 # * Have postfix listen on all network interfaces.
+# * Make outgoing connections on a particular interface (if multihomed) so that SPF passes on the receiving side.
 # * Set our name (the Debian default seems to be "localhost" but make it our hostname).
 # * Set the name of the local machine to localhost, which means xxx@localhost is delivered locally, although we don't use it.
 # * Set the SMTP banner (which must have the hostname first, then anything).
 tools/editconf.py /etc/postfix/main.cf \
 	inet_interfaces=all \
+	smtp_bind_address=$PRIVATE_IP \
+	smtp_bind_address6=$PRIVATE_IPV6 \
 	myhostname=$PRIMARY_HOSTNAME\
 	smtpd_banner="\$myhostname ESMTP Hi, I'm a Mail-in-a-Box (Ubuntu/Postfix; see https://mailinabox.email/)" \
 	mydestination=localhost