Block spoofing emails

Hi,

I recommend setting SPF-records for your domain and enabling "Perfom SPF check" in SMTP->Antispam.

Hi Josef, thank you for your reply. 

SPF is always enabled and records are update-to-date, this seems to be an open relay problem in UTM.

just send an email from an external source as postmaster@yourdomain through the firewall and you have your open relay... no checks at all will be applied...

Which result do you see for the mail from supertool@mxtoolboxsmtpdiag.com to test@mxtoolboxsmtpdiag.com ?

Hi,

maybe you are completely on the wrong track, I don't think that there is a open relay problem in the UTM.

What was your problem:

Johnny Long said:

lot of our users have received spoofing emails that appear from themself

How exactly look this emails? Are the spoofed senders email-addresses maybe only in the body and not in the envelope FROM. Check the SMTP Log in the Mail Manager, what exactly is the from address here.

If these from-domain is your domain, then check your SPF-domainsettings in your DNS.

This is the email header looks like

Received: from EX2016-MDB-C.MYDOMAIN.Hosted (10.2.4.212) by
 EX2016-MDB-C.MYDOMAIN.Hosted (10.2.4.212) with Microsoft SMTP Server
 (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8
 via Mailbox Transport; Wed, 4 May 2022 04:16:58 +1000
Received: from EX2016-MDB-AN.MYDOMAIN.Hosted (10.2.2.129) by
 EX2016-MDB-C.MYDOMAIN.Hosted (10.2.4.212) with Microsoft SMTP Server
 (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id
 15.1.2308.8; Wed, 4 May 2022 04:16:58 +1000
Received: from ip-1xxxxxxxx-2.compute.internal (10.2.6.109) by
 EX2016-MDB-AN.MYDOMAIN.Hosted (10.2.2.129) with Microsoft SMTP Server
 (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2308.8
 via Frontend Transport; Wed, 4 May 2022 04:17:40 +1000
Received: from [10.2.6.120] (helo=mail.MYDOMAIN.net)
	by ip-1xxxxxxxx-2.compute.internal with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256)
	(Exim 4.90_1)
	(envelope-from <lxxxxx@xxxxx.com>)
	id 1nlx5g-0003dL-JJ
	for lxxxxx@xxxxx.com; Wed, 04 May 2022 04:17:40 +1000
Received: from mail.ghfhgdg.com ([85.239.34.13]:33068)
	by mail.MYDOMAIN.net with esmtps  (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
	(Exim 4.95)
	(envelope-from <lxxxxx@xxxxx.com>)
	id 1nlx5X-00057p-2m
	for lxxxxx@xxxxx.com;
	Wed, 04 May 2022 04:17:32 +1000
Received: from ip63.ip-51-91-202.eu ([51.91.202.63]:53416 helo=galsan.com)
	by mail.ghfhgdg.com with esmtpsa  (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384
	(Exim 4.95)
	(envelope-from <lxxxxx@xxxxx.com>)
	id 1nlx5V-0007v8-Vs
	for lxxxxx@xxxxx.com;
	Tue, 03 May 2022 21:17:28 +0300
X-SASI-Hits: BODYTEXTH_SIZE_3000_MORE 0.000000,
	BODYTEXTP_SIZE_3000_LESS 0.000000, BODYTEXTP_SIZE_400_LESS 0.000000,
	BODY_SIZE_10000_PLUS 0.000000, BODY_SIZE_25K_PLUS 0.000000,
	EXCESSIVE_SUBDOMAINS7 3.000000, FRAUD_ATTACH 0.050000,
	FROM_NAME_ALLCAPS 0.100000, FROM_RCPT_DOMAIN_NOT_IN_RCVD 0.000000,
	FROM_SAME_AS_TO_DOMAIN 0.000000, HTML_90_100 0.100000, HTML_95_100 0.100000,
	IMGSPAM_TABLE_1 0.000000, NO_FUR_HEADER 0.000000, NO_URI_HTTPS 0.000000,
	OUTBOUND 0.000000, OUTBOUND_SOPHOS 0.000000, SENDER_NO_AUTH 0.000000,
	SINGLE_HREF_URI_IN_BODY 0.000000, SINGLE_HREF_URI_WITH_EMAIL 0.000000,
	__ANY_URI 0.000000, __ATTACHMENT_PHRASE 0.000000, __BODY_NO_MAILTO 0.000000,
	__BULK_NEGATE 0.000000, __CSHC_NS_B_FN_FA 0.000000, __CT 0.000000,
	__CTYPE_HAS_BOUNDARY 0.000000, __CTYPE_MULTIPART 0.000000,
	__CTYPE_MULTIPART_ALT 0.000000, __DATA_URL_SCHEME 0.000000,
	__DATE_TZ_HK 0.000000, __DQ_NEG_DOMAIN 0.000000, __DQ_NEG_HEUR 0.000000,
	__DQ_NEG_IP 0.000000, __EXCESSIVE_SUBDOMAINS6 0.000000,
	__EXCESSIVE_SUBDOMAINS7 0.000000, __FAX_BODY 0.000000,
	__FILESHARE_PHRASE 0.000000, __FRAUD_ANTIABUSE 0.000000,
	__FROM_DOMAIN_IN_ANY_TO1 0.000000, __FROM_DOMAIN_IN_RCPT 0.000000,
	__FROM_NAME_NOT_IN_ADDR 0.000000, __FROM_NAME_NOT_IN_BODY 0.000000,
	__FUR_RDNS_SOPHOS 0.000000, __HAS_FROM 0.000000, __HAS_HTML 0.000000,
	__HAS_MSGID 0.000000, __HTML_AHREF_TAG 0.000000, __HTML_BAD_END 0.000000,
	__HTML_TAG_CENTER 0.000000, __HTML_TAG_IMG_X2 0.000000,
	__HTML_TAG_TABLE 0.000000, __IMGSPAM_TABLE_1 0.000000,
	__IMG_THEN_TEXT 0.000000, __MIME_HTML 0.000000, __MIME_TEXT_H 0.000000,
	__MIME_TEXT_H1 0.000000, __MIME_TEXT_H2 0.000000, __MIME_TEXT_P 0.000000,
	__MIME_TEXT_P1 0.000000, __MIME_TEXT_P2 0.000000, __MIME_VERSION 0.000000,
	__MULTIPLE_URI_TEXT 0.000000, __OUTBOUND_SOPHOS_FUR 0.000000,
	__OUTBOUND_SOPHOS_FUR_IP 0.000000, __OUTBOUND_SOPHOS_FUR_RDNS 0.000000,
	__PHISH_PHRASE10_D 0.000000, __RCPT_DOMAIN_IS_FROM_DOMAIN 0.000000,
	__SANE_MSGID 0.000000, __SUBJ_ALPHA_END 0.000000, __TAG_EXISTS_HTML 0.000000,
	__TO_DOMAIN_IN_FROM 0.000000, __TO_DOMAIN_IN_MSGID 0.000000,
	__TO_MALFORMED_2 0.000000, __TO_NO_NAME 0.000000,
	__URI_EMAIL_IN_QUERY 0.000000, __URI_IN_BODY 0.000000, __URI_MAILTO 0.000000,
	__URI_NOT_IMG 0.000000, __URI_NO_PATH 0.000000, __URI_NO_WWW 0.000000,
	__URI_NS 0.000000, __URI_WITHOUT_PATH 0.000000
X-SASI-Probability: 30%
X-SASI-RCODE: 200
X-SASI-Version: Antispam-Engine: 4.1.4, AntispamData: 2022.5.3.173622
From: HOA ORDERS <lxxxxx@xxxxx.com>
To: <lxxxxx@xxxxx.com>
Subject: Requested HOA Letter
Date: Wed, 4 May 2022 02:17:27 +0800
Message-ID: <20220504021727.BFD45D6D250BF3FA@xxxxx.com>
MIME-Version: 1.0
Content-Type: multipart/alternative;
	boundary="----=_NextPart_000_0012_1F95ED89.02DDA1DF"
X-AntiAbuse: This header was added to track abuse, please include it with any abuse report
X-AntiAbuse: Primary Hostname - mail.ghfhgdg.com
X-AntiAbuse: Original Domain - xxxxx.com
X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12]
X-AntiAbuse: Sender Address Domain - xxxxx.com
X-Get-Message-Sender-Via: mail.ghfhgdg.com: authenticated_id: dennis@ghfhgdg.com
X-Authenticated-Sender: mail.ghfhgdg.com: dennis@ghfhgdg.com
X-Source:
X-Source-Args:
X-Source-Dir:
Return-Path: lxxxxx@xxxxx.com
X-MS-Exchange-Organization-Network-Message-Id: 2be4961d-c269-4b3a-e3f4-08da2d3135da
X-MS-Exchange-Organization-AVStamp-Enterprise: 1.0
X-MS-Exchange-Organization-AuthSource: EX2016-MDB-AN.MYDOMAIN.Hosted
X-MS-Exchange-Organization-AuthAs: Anonymous
X-MS-Exchange-Processed-By-BccFoldering: 15.01.2308.008

Ok, I suggest xxxxx.com stands for your domain.

Which hop is your UTM? mail.MYDOMAIN.net?

How looks your SPF-Setting in the DNS?

Yes, mail.MYDOMAIN.net is the UTM hop.

This is what the SPF settings look like:
v=spf1 mx ip4:13.xx.xx.xx ip4:13.xx.xx.xx ip4:13.xx.xx.xx ip4:13.xx.xx.xx ip4:13.xx.xx.xx include:spf.messagelabs.com include:spf.protection.outlook.com include:spf.smtp2go.com ~all

Can anyone spot any issues?

The results show as

SendSMTPCommand: You hung up on us after we connected. Please whitelist us. (connection lost)

Ok so you use "Softfail" (~all) in your SPF-policy, these will not stop the spoofed mail on the UTM.

More details see here Sophos UTM: Enable Sender Policy Framework (SPF)

"... Your SPF record should contain the token "-all" at the end not "~all". This is a common reason why people are not rejecting spoofed mail as expected."

Hi Josef, I know we use "Softfail", but we have "Perform SPF check" turned on and I can see a lot of emails got rejected because of SPF check failed.

I still think we have is an open relay problem, not an SPF problem.

If you don't check your own mail logs after doing the OpenRelay test, you would never really know this.

PS: and i think SPF soft-fail will pass UTM-Spam filter. (you may check SPF-records from SPF-blocked mails)

If you don't check your own mail logs after doing the OpenRelay test, you would never really know this.

PS: and i think SPF soft-fail will pass UTM-Spam filter. (you may check SPF-records from SPF-blocked mails)