I changed my inet_interfaces setting this morning, and stopped and started postfix (postfix stop; postfix start)
# postconf -n inet_interfaces inet_interfaces = 127.0.0.1, 65.121.55.42 But when I am trying to send emails to a certain company, I am getting an SPF error (even though my entire netblock is in the SPF settings) that claims I am connecting from a different IP (an IP that is assigned to the same physical machine as postfix) than specified in inet_interfaces. status=bounced (host mail.synology.com[59.124.61.242] said: 550 5.7.1 <supp...@synology.com>: Recipient address rejected: Message rejected due to: SPF fail - not authorized. Please see http://www.openspf.net/Why?s=mfrom;id=(*munged*);ip=65.121.55.45;r=supp...@synology.com (in reply to RCPT TO command)) covisp.net. 86400 IN TXT "v=spf1 mx a ip4:65.121.55.40/29 -all" I know this is problem with the receiver, but I am concerned that it is reporting an IP that postfix shouldn't be using (.45 instead of .42). <http://www.postfix.org/postconf.5.html#inet_interfaces> When inet_interfaces specifies just one IPv4 and/or IPv6 address that is not a loopback address, the Postfix SMTP client will use this address as the IP source address for outbound mail. Support for IPv6 is available in Postfix version 2.2 and later.
