SPF records for SMTP out of date?

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3 posts Page 1 of 1
by msiegen » Tue Jul 05, 2022 11:39 am
I'm observing mail sent though Sonic's SMTP serving failing SPF checks. This could lead to mail being dropped or marked as spam by the destination.

Example headers for a message from a @sonic.net address to a @live.com address:

Code: Select all

Authentication-Results: spf=softfail (sender IP is 157.131.0.51)
 smtp.mailfrom=sonic.net; dkim=none (message not signed)
 header.d=none;dmarc=none action=none header.from=sonic.net;compauth=pass
 reason=105
Received-SPF: SoftFail (protection.outlook.com: domain of transitioning
 sonic.net discourages use of 157.131.0.51 as permitted sender)
Received: from b.mail-forward.sonic.net (157.131.0.51) by
 VI1EUR06FT059.mail.protection.outlook.com (10.13.6.222) with Microsoft SMTP
 Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id
 15.20.5395.14 via Frontend Transport; Tue, 5 Jul 2022 18:12:27 +0000


157.131.0.51 is indeed not permitted:

Code: Select all

$ dig +short -t txt sonic.net
"v=spf1 include:mail.sonic.net ~all"
$ dig +short -t txt mail.sonic.net
"v=spf1 ip4:64.142.105.165 ip4:64.142.111.80 ip4:64.142.111.50 ip4:69.12.208.71 ip4:69.12.221.231 ip4:157.131.224.64/26 ip4:184.23.168.64/28 ip6:2001:5a8:601:4000::0/64 -all"


Should this SPF record be updated to match the current set IPs used for SMTP?
by kgc » Tue Jul 05, 2022 12:25 pm
Yes, mail doesn't typically flow out the IP you've seen here but it can under some circumstances. Updated. Thanks for the report.
Kelsey Cummings
System Architect, Sonic.net, Inc.
by msiegen » Tue Jul 05, 2022 1:37 pm
Awesome, thanks for the speedy fix!
3 posts Page 1 of 1

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