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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93 views

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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158 views

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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267 views

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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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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outlook.com breaks DKIM when forwarding for multipart messages

When I send a multipart email from my server to outlook.com, but have it forwarded to a Gmail account (or anywhere else), DKIM fails, with the message "body hash did not verify", even though as far as ...
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368 views

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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2answers
90 views

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 order to ...
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2answers
133 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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2answers
100 views

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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1answer
211 views

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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1answer
90 views

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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1answer
87 views

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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1answer
102 views

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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1answer
179 views

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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3answers
1k views

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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1answer
107 views

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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628 views

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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1answer
178 views

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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1answer
35 views

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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2answers
341 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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1answer
3k views

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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2answers
480 views

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 DKIM or SPF passes. ...
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1answer
418 views

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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1answer
411 views

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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1answer
3k views

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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1answer
1k views

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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1answer
60 views

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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2answers
88 views

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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1answer
92 views

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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91 views

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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1answer
730 views

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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2answers
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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4answers
170 views

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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1answer
80 views

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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1answer
152 views

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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3answers
8k 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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2answers
666 views

Why did spoof email receive a “pass”? And why didn't it show up in the aggregate report?

Good Morning All, I've been thrown into the deep end with a request from my director. I know little of DMARC and email spoofing in general, but I'm trying to somehow weed out WHY this spoof email "...
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1answer
666 views

How to create email that will fool DKIM verifier?

Sammy the sender is sending email to Rita the recipient. I know Sammy will apply a DKIM signature to the email and Rita is going to check the DKIM signature with a DKIM validator. I am a malicious ...
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1answer
583 views

Which Domain Validation category does DKIM fall under?

I know that the categories of domain validation are: Regular SSL Multi Domain Validation Wildcard Certificates Premium SSL But I am not sure under which of the above does DKIM falls.
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2answers
609 views

Is reverse DNS a must have to prevent emails delivered as spam?

I was considering setting up my own mail server and one of the things I've read about is that I must setup reverse DNS to do not get caught by a spam filter. Is that really a must? Aren't SPF and ...
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1answer
142 views

Missing DKIM, but having digital signature, will this help mitigate ending up in spam folder?

According to this mail tester: https://www.mail-tester.com I am quite fine with sending emails from my domain's email info@vlastimilburian.cz According to this mail tester: http://mailtester.com/...
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1answer
192 views

How can I prove that mail sent was NOT caused by the newly deployed DMARC policy?

I understand that by publishing an initial p=none policy, you basically instruct recipients that participate in DMARC to NOT treat incoming mail any different than how they did before a DMARC policy ...
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1answer
160 views

DMARC annoyances

I've recently setup a mail server, which will be handling email for multiple people and domains. Appropriate SPF, DKIM, DMARC and ADSP records have been added, yet I'm getting something confusing: ...
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1answer
925 views

DKIM/SPF problem causing lots of DMARC reports

I get messages from "noreply-dmarc-support@google.com" with a DMARC report as follows: <?xml version="1.0" encoding="UTF-8" ?> <feedback> <report_metadata> <org_name>...
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2answers
3k views

Why do email that didn't pass SPF checks go to my mailbox?

I tried a website that supposedly sends spoofed email. I sent myself an email impersonating another email address and the message showed up in my yahoo mailbox even though according to the headers it ...
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2answers
282 views

PGP Key Signing Robot DKIM Verified Emails

It occurred to me that DKIM verified emails, from major players (e.g., GMail), could open the door to more modern OpenPGP robot key signing authorities. The idea would be to ask people to send a key ...