Questions tagged [dkim]

DomainKeys Identified Mail (DKIM) is an email authentication method designed to detect email spoofing by allowing the receiving party to verify with the sending party that the email actually originates from their domain.

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Why is DMARC Passing, when it seems like there is no alignment?

I have set adkim=s and aspf=s, the DMARC check on mxtoolbox.com passes all tests. However, I'm using the default DKIM from microsoft, so from my understanding DMARC should fail since the alignment ...
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Authorizing 3rd Party Envelope Sender to Impersonate Header Sender

Rewriting for clarity: This is regarding emails send from a 3rd party marketer spoofing one of our email addresses in the message header from field. In these emails the envelope sender would come ...
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How did the email pass DKIM?

I am trying to figure out how this one phishing email (used our Company's domain as from) was able to bypass the O365 Spamfilter. Looking at the Header it looks like they passed the DKIM even though ...
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How did this paypal spoof email pass SPF, DKIM and DMARC

This mail that got through has me stumped. It appeared to me as being from PayPal <unclaimedproperty@paypal.com> in my Inbox. I happened to look at the original and it says SPF, DKIM and DMARC ...
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Rejected because of DKIM check fail; alignment check fail

I am testing my mail server setup with this tool https://email-test.had.dnsops.gov/ and I am getting suspicious that the tool may not be working right. From what I understand it reports that my ...
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What is the point of having SPF and DKIM set up, but having DMARC with policy=none?

Under this FAQ it says that using policy=none is a way for domain owners to monitor forged emails, without having to set up SPF/DKIM. But what im wondering, because i dont fully understand what SPF/...
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Why do I need DMARC on top of SPF and DKIM? [duplicate]

If SPF is verifying against a set of IP records if the incoming email from a domain was sent from an authorized host piggybacking on the DNS and DKIM does touch the signature of the email and ...
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Whitelisting Email Service for Anti-Spoofing and DMARC

My company uses an Anti-Spoofing Protection based on the SPF Record and has implemented DMARC. Often our users correspond via a "secure" messaging platform like Proofpoint/ZIX/IronPort from ...
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Spoofed email? "X-Source-Sender" and "Received" headers look dodgy

I got sent an email from someone in response to an over 2 year old exchange, and the contents of it look like spam to me. Checking the headers the following looks normal: Return-Path Received & ...
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SPF fail, DKIM pass, where did the emails originate from [closed]

I have been a victim of a fraud where my solicitor's email address was used to dupe me out of a house purchase deposit. How do I determine where the emails originated from - did the crooks use emails ...
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Does gmail still ignore DKIM if SPF passes, DMARC style?

This blog post from 2016 shockingly implies that gmail will accept an email if either SPF or DKIM passes. We use G suite SMTP servers, therefore SPF provides almost zero protection from spoofing. Is ...
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DKIM and CNAME or DNAME

As far as I understand, there should be no problems with using CNAME or DNAME records in connection with DKIM. That is, while the DKIM record for verifiying a mail from someone@example.com wants to be ...
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How do I run through the DKIM authentication?

I am currently reading on DKIM authentication for email and I would like to manually try to run through it (to facilitate my understanding of DKIM), but I would like to verify if it is possible to do ...
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Do we need SPF when we have DKIM? [duplicate]

I always thought that to authenticate email we needed both SPF and DKIM (and DMARC). But email is confusing and recently I found myself asking why we can't do with just SPF or DKIM. I then discovered ...
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DMARC report for mails I didn't send

I set up DKIM, DMARC and SPF on my domain/server a few years ago, and never touched it again since then. Here are my DNS records (my domain is mydomain.com and my IP addresses are 1.1.1.1 and 2001::1)...
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Theoretical DKIM Question

I have been playing around with sending emails via telnet using text commands. Theoretically... Say I send an email from a typical mail agent that adds a dkim signature from a@a.com to b@b.com. ...
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Why do we need DKIM to be used along with S/Mime?

S/Mime can be used to encrypt email and it can also be used by the sender to provide his digital signature so that the recipient is able to confirm the authenticity of the sender. Why then do we ...
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Why is DMARC failing when SPF and DKIM are passing?

I've seen this question asked before, but unfortunately, don't understand the responses. I think its something to do with "from" headers being defined differently by different standards. I've added ...
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3 votes
2 answers
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Does DKIM protect the whole body message?

From RFC6376 #page-29, it says: In hash step 1, the Signer/Verifier MUST hash the message body, canonicalized using the body canonicalization algorithm specified in the "c=" tag and then ...
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8 votes
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How did a phishing email pass SPF, DKIM and DMARC?

A friend received a spoofed email (from Bank of America using an uber.com address) which was correctly identified as 'spam' by Gmail. However, looking at the raw message it seems to have passed SPF, ...
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What is the reason for DMARC spec to not require specifically SPF or DKIM pass?

DMARC produces "pass" result if and only if at least one of SPF and DKIM checks pass. It has been noted that DKIM provides stronger protection of the two (if implemented properly). But, in ...
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4 votes
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215 views

Email verification by sending mail instead of receiving

I have an app whose main purpose is to help people track emails they send. In most user onboarding, The user is sent a secret URL via email. They validate by clicking a link to return the secret. ...
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SPF, DKIM and DMARC - How do receiving/recipient mail servers know how and when to validate the mail?

I have spent a bit of time researching SPF, DKIM and DMARC mechanisms however If I understand correctly, these help the recipient to confirm whether the domain is legitimate but only if they have ...
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dkim passes under a different domain's dkim

I read that a SPF fail with DKIM pass means someone has forwarded an email with our domain name attached. I haven't sent any emails to this domain. Is this domain trying to send emails with my domain? ...
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What's the use of DKIM/SPF if it only validates the Enveloppe From?

DKIM and SPF are mentioned as powerful mitigations for having your domain abused for phishing. But when I send a mail like this: Return-Path: <me@mydomain.example.com> From: Citibank security ...
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Understanding DKIM validation

DKIM, as read by rfc4871, states to make address forgery more difficult besides protecting sender identity and integrity of the mail. I have been searching for the details, which precise validation ...
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Giving a PFX cert to a 3rd party email service for DKIM?

My organization is working with a vendor that needs to send emails on our behalf. They want us to import a PFX certificate into a DKIM key. We want to understand the implications first. What ...
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1 answer
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Is it bad to use DKIM DNS without signing mails?

Does it provide any trust at all to have DKIM set up correctly in my DNS but not sign any emails? I could not find any information about that. Now, if I send an email to a domain/server with DMARC ...
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7 votes
3 answers
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Why does DKIM verification succeed with a signature from Yahoo when all headers are spoofed to look like GMail?

Today I got a scam e-mail which I decided to disect. I quickly found that it was sent from a GMail address (From, Reply-To, Return-Path) but that the mail itself came from Yahoo. HELO from Yahoo ...
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2 votes
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Is it safe to post the output of Linux dig (DNS) commands?

I need help debugging/troubleshooting a DNS/DKIM issue over on ServerFault, but it looks like I need to paste the results of running: dig my-dns-record.example.com CNAME ...where my-dns-record....
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How should I configure DMARC (or DKIM?) to deal with OWA forwarding changing email bodies?

For my own domain (mydomain.com, hosted with a free G Suite), I have setup DMARC in testing mode: v=DMARC1; p=none; sp=reject; aspf=s; adkim=s; rua=mailto:dmarc@mydomain.com I have sent out test ...
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1 vote
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How to disable email for a subdomain without using SPF

I am working on a tool that checks SPF records, and would like a way to be able to disable email from a testing subdomain, and its children, so that my test domains are not easy targets for spammers ...
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Are emails from the Necurs bot net DKIM and/or SPF signed?

As the questions title already asks: Are emails sent by Necurs DKIM and/or SPF signed? Or are they unsigned and simply spoofed?
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1 vote
2 answers
561 views

SPF and DKIM passes for SPAM message when using SES and Google Mail

We have websites hosted on AWS, are using SES to send out mailings, and use Google Mail for sending and receiving company mail. Every so often I receive SPAM emails to my Priority Inbox in Google ...
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6 votes
2 answers
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Finding DKIM selectors without mailing

Is there any way to find out what selectors are used by a domain in their DKIM record without access to an e-mail send from that domain? So to clarify, let's say I know example.com has DKIM ...
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3 votes
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DMARC policy result when exactly one of SPF and DKIM fails and exactly one succeeds

E-mail forwarding can break SPF, but it should not break DKIM. I want to make a DMARC policy that will evaluate to "pass" when either DKIM or SPF passes, and "fail" when neither ...
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3 votes
1 answer
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Understand DMARC report before starting quarantine

I work for a small company. We have lot of IP black listed because of spamming. We decided to setup dmarc for our mail server. This has been setup and is working correctly. The issue now is that in ...
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5 votes
1 answer
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Why set up DMARC for SPF if it's already set up for DKIM?

I have SPF and DKIM. I'm planning on adding DMARC to tell receivers to expect SPF and/or DKIM. I've read that it's best to set DMARC up with both SPF and DKIM, but I don't understand exactly when ...
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Dmarc: Why do I have dkim=fail, spf=fail and result=pass

I have set up my company dmarc. It is in test mode and I regularly receive reports. Some seem weird to me and I would like to understand. For example, I have received a report with SPF and dkim failed,...
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3 votes
1 answer
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How to read dmarc record for a report?

I have a dmarc file containing some record. I am bit surprised by the result and I would like to make sure I am reading it correctly. Here is the record: <record> <row> &...
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Why is DKIM configuration testing not working the same for every test site?

basically, I have setup spk, dkim and dmarc for mail authentication. For this, I used this tuto. All worked correctly and I got this result: seems like everything OK. Now to confirm everything is ...
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Could DKIM be used as a proof that an e-mail was sent by a given party?

For quite some time, I was wondering if there are ways I could record forms of communication with, say, Facebook servers and have a plausible proof that a specific event (such as receiving a private ...
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1 vote
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Is there a passive way to verify DKIM implementations (on DNS level) without triggering an actual email event?

I wondered if there is a way to verify the correctness/validity of DKIM implementations without actually triggering an email event or sending an email to an external validator. So, remotely, on any ...
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Why CA are mandatory to trust our public key? What if we publish the public key via DNS like in DKIM? [duplicate]

Why we need trusted third party to sign our public key to be trusted? we can publish it via DNS and it will be trusted. Isn't like that work DKIM? Why we don't do same thing for HTTPS?
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6 votes
1 answer
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Why is still so easy to send phishing emails?

When I first started playing around with how SMTP worked over 20 years ago, I remember being somewhat surprised how easy it was to make an email appear in someone else's mailbox that looked like it ...
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4 votes
2 answers
3k views

How can I prevent email spoofing from my domain?

I recently registered a domain name, and set up an email account tied to it with Zoho mail. I'm concerned about making sure all emails from this domain are signed to prevent spoofing. I've enabled ...
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4 answers
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Suspicious Entry in DMARC Report

I recently contacted a vendor of security-related development libraries to ask for a quote (I won't name them yet). The next day, Postmark sent me my weekly DMARC report - and it contained 2 failed ...
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1 vote
1 answer
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Verify senders of earlier emails in chain

I know that an emails' sender can be verified e.g. through DKIM. If I receive an email chain containing replies, forwards, etc. is there any way to verify the sender of other (earlier) emails in the ...
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3 votes
1 answer
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Are high levels of email spam normal?

I have got my SPF, DKIM & DMARC records correctly setup and I have started using a DMARC analysis service. One thing I have noticed is the volume failures. For example, in the last 3 days I have ...
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4 votes
3 answers
12k views

Security of SPF vs SPF and DKIM in email

I am looking for an email provider that I will use with custom domain, one provider is cheaper but has only SPF while the other is more expensive but uses both SPF and DKIM and I'm not sure if paying ...
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