DomainKeys Identified Mail is a scheme for signing and verifying email messages to confirm that that the source hasn't been forged, and is typically implemented by MTAs. The source MTA adds a header to the message body containing a signature, and the destination MTA verifies this signature against a ...

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42
votes
6answers
7k views

Fighting Spam - What can I do as an: Email Administrator, Domain Owner, or User?

This is a Canonical Question about Fighting Spam. Also related: How to stop people from using my domain to send spam? What are SPF records, and how do I configure them? There are ...
22
votes
4answers
9k views

DKIM sign outgoing mail from any domain (with Postfix and Ubuntu)

I got DKIM setup on my mail server (postfix and ubuntu) so it signs outgoing emails. I used these instructions: https://help.ubuntu.com/community/Postfix/DKIM However, I need it to sign emails from ...
10
votes
2answers
1k views

How did spammer spoof emails with my google apps domain (it even has DKIM!)

I have been getting a lot of bounce-backs lately. I thought my google apps account has been compromised, but there is no activity on my apps account, and there is certainly no malicious user that I ...
8
votes
1answer
463 views

Are there any pitfalls to DKIM?

We are considering implementing DKIM, the pros seem pretty obvious. Are there any cons? I know this is a bit vague and possibly subjective so I will accept what seems to me to be the most complete ...
7
votes
4answers
3k views

Getting Exchange to do DKIM

Having read Jeff's blog post about Email and DKIM, I'm thinking it might be good to DKIM all mail coming out of our Exchange 2003 servers. Whats a good way of going about that?
6
votes
4answers
922 views

Why does my mail get marked as spam?

I Have the server "afspraakmanager.be". It matches everything not to be a spam server.(it isn't by the way): it has reverse dns, spf,dkim,... . But hotmail marks it as spam. I think the problem is ...
5
votes
3answers
2k views

PTR OK, SPF, DKIM passed but email messages are marked as Spam by Google?

# host 1.2.3.4 4.3.2.1.in-addr.arpa domain name pointer mail.domain.vn. # dig +short txt domain.vn "v=spf1 a mx ptr -all" # dig +short txt mail.domain.vn "v=spf1 a -all" Here's an email header ...
5
votes
3answers
914 views

DKIM vs Domain Keys

I've configured DKIM (milter-dkim) on my mail server. Incoming e-mail sent from my domain now containts the following header: X-DKIM: Sendmail DKIM Filter v2.8.3 MYDOMAIN.com o7FLH1Wa032083 ...
5
votes
1answer
132 views

SPF vs. DKIM - The exact use cases and differences

I'm sorry for the vague title. I don't fully understand why SPF and DKIM should be used together. First: SPF can pass where it should fail if the sender or DNS is "spoofed" and it can fail where it ...
5
votes
2answers
1k views

What are the advantages of DKIM?

After making my server sign outgoing email I started to wonder what the benefits are. This is the opposite of a previously asked question. Naively I see two benefits: We can throw away all emails ...
5
votes
3answers
4k views

Setting up DKIM for multiple domains on same host

I have DKIM set up for one domain and it works properly. I am trying, though, to set it up for another domain name on the same machine. In short, I am sending registration and password recovery emails ...
5
votes
1answer
115 views

Designating A DKIM Signer Other Than The “From” Domain

A few months ago, I implemented SPF/DKIM/DMARC for my three-person company. After a trial period, I switched our DMARC to "p=reject", so that emails are rejected if they fail SPF/DKIM. Generally, it ...
4
votes
3answers
3k views

Why is my email failing Gmail's DKIM test?

I have a message that was rejected by Gmail, I don't know why. It passes SPF. We aren't using DKIM. Do I need to set up DKIM? I am in control of "example.com". Our mail server is "server.example.com" ...
4
votes
2answers
2k views

Remove “via” from emails sent to Gmail from Amazon SES

When sending emails from Amazon SES, gmail shows "sent via amazonses.com". How do I remove this? According to Google, I'm a sender and I don't want my recipients to see the "via" link. What can I ...
4
votes
3answers
68 views

Will mailing lists “break” if SPF is too restrictive?

I have recently configured my own mail server (Linux-based postfix + dovecot scenario). This is just for personal use - I have no bulk mail going out, no automatically generated mail outbound from the ...
4
votes
1answer
232 views

DKIM and SPF for a subdomain

I manage a VPS on Linode accessed through subdomain.example.com and I need to send email from this subdomain. I can't set any TXT records in Linode DNS manager because the name servers for example.com ...
4
votes
2answers
2k views

Postfix with DKIM on Ubuntu

I want to improve deliverability for my outgoing emails with DKIM. I've gotten dkim-filter installed for postfix, using this tutorial https://help.ubuntu.com/community/Postfix/DKIM It seems to be ...
4
votes
1answer
302 views

Does DKIM works with subdomains?

ISP's recommend you segment your marketing and transactional emails by using different IPs. I want to start using DKIM, but since DKIM is a domain based reputation system I wonder if signing with the ...
3
votes
3answers
6k views

What exactly is a X-YMailISG header?

Finally ... our emails are being seen by Yahoo! not as junk anymore. Hurray! However I notice that the Yahoo! receiving MTA adds in a X-YMailISG header. It's very large ... 2**10 bits? Now that ...
3
votes
2answers
2k views

SPF hardfail and DKIM failure when recipient has e-mail forwarding

I configured hardfail SPF for my domain and DKIM message signing on my SMTP server. Since this is the only SMTP server that should be used for outgoing mail from my domain, I didn't foresee any ...
3
votes
2answers
46 views

Is there anything bad about DKIM-signing mail without the key in DNS?

At a site that I manage, we send out emails for many customer domains. Some of them have our DKIM key in DNS, some don't. From what I can tell: Signature verification failure does not force ...
3
votes
1answer
360 views

What problems can an ADSP record in DNS cause for mailflow?

ADSP is an entry in DNS that works allows a domain owner to assert that all email must be signed with DKIM. (similar to the -all and ~all in SPF/SenderID). Messages that fail ADSP policy may be ...
3
votes
1answer
9k views

Yahoo Domain Keys setup, getting dkim=permerror (no key)

I'm working on getting DKIM installed on my outgoing mail server, to help my email deliverability to my Yahoo clients (all legit emails, etc, no spamming). I've got DKIM-Signature: and ...
3
votes
1answer
2k views

postfix + opendkim not signing correctly. how to debug this?

EDIT: I did get a little further but all posts on my search say permissions are wrong or regenerate key but I fixed that to be 644 as well as owned by DKIM AND I keep regenerating the key but it is ...
3
votes
1answer
66 views

What is the benefit of using DKIM to sign Content Type?

DKIM has the ability to sign headers on a per-header basis. I looked at Google's headers, and they DKIM sign ContentType. What is the security benefit of signing ContentType?
2
votes
3answers
840 views

Should I reject email on SPF and/or DKIM failures? [duplicate]

I’m administering a mail server (cPanel/WHM) running Exim. It handles normally a few hundreds incoming emails per day for our customers. I’m not sure if I should reject SPF and/or DKIM failures for ...
2
votes
3answers
188 views

Email won't send

2013-01-18 10:33:04 cwd=/home/USER/public_html/clients 3 args: /usr/sbin/sendmail -t -i 2013-01-18 10:33:04 1TwDwG-00023y-Ks <= USER@host.mydomain.com U=USER P=local S=3993 ...
2
votes
2answers
725 views

What is the correct mail set up for multiple domains on one server?

I have a machine (centos 5) with one external ip address. On that machine I have many virtual hosts with a few different top level domain names and sub-domains under those eg. sub1.domain1.com ...
2
votes
1answer
3k views

How do I use OpenDKIM with multiple domain names on a single server?

How do I use OpenDKIM with multiple domain names on a single server? I own 3 domain names, and I have a single server that's running postfix for sending email. How do I use OpenDKIM? Can I use the ...
2
votes
1answer
184 views

Publishing long domain key records in bind9

I am setting up a mail system based on exim4. This system implements DKIM signing and checking (among other things). Signing seems to work without problems but checking doesn't work and exim4 ...
2
votes
2answers
76 views

What is the Value of using DKIM to sign mail when the from header doesn't match?

My domain is domain.tld, where I have DKIM functioning just fine. All of my domain emails are signed, and pass. I have a need now to send mail on behalf of my customers occasionally - ie: send email ...
2
votes
1answer
66 views

Understanding the many “FROM” addresses that apply to SenderID, DKIM, and SPF

Can someone tell me when and why a client, MTA relay, Unix .Forward, anonymous relay, or listserver will create, or alter these headers: Resent-Sender: Resent-From: Sender: From: If you can please ...
2
votes
1answer
632 views

Mail classified as spam, but passes SPF and DKIM

I have configured Postfix to be responsible for subdomain.example.com (google apps is responsible for example.com so I didn't want to mix the two). As I mentioned in question title, SPF and DKIM ...
2
votes
3answers
3k views

DKIM- Filter No Signature Data

I have installed DKIM-Filter on Postfix after reading this tutorial http://www.unibia.com/unibianet/systems-networking/how-setup-domainkeys-identified-mail-dkim-postfix-and-ubuntu-server My email ...
2
votes
2answers
4k views

gmail dkim=neutral (no signature)

After testing much and retracing my steps, I still cannot get google mail to validate. My mail server is Debian 5.0 with exim Exim version 4.72 #1 built 31-Jul-2010 08:12:17 Copyright (c) ...
2
votes
2answers
219 views

How important is sender validation, and what matters?

When I started learning how to configure email, SPF existed but there were doubts about whether it was a good thing, and the value of offering SPF records in DNS. Now it seems that it is widely ...
2
votes
2answers
366 views

SMTP server on Win2008, SPF ecc

I want be able to send outgoing email from my website. I want to setup Win2008 smtp to be able to send them respecting all the spam rules. My checklist is: the smtp should be able to accept ...
2
votes
3answers
909 views

no signing table match in opendkim

I have opendkim installed on centos. I am using postfix as MTA and dovecot for imap/pop... Now the problem is am trying to setup dkim for my domian. The mails are send from a sub domain ...
2
votes
1answer
52 views

When creating DomainKeys does it matter if I use o=~ or o=-?

I used this utility to create my DKIM key (1024 bit size), since Gmail has been blocking us (we had an old joomla install exploited, was around before me). And I got this back: Your Selector Record: ...
2
votes
1answer
611 views

How to fix DKIM for mail on VPS hosting?

I have a hosted VPS that is fully managed by the hosting company. For weeks they cannot figure out how to get DKIM working for my emails, even though in cPanel's Email Authentication section says DKIM ...
2
votes
0answers
363 views

Exim 4.71 does not add DKIM signature to outgoing emails

I am trying to add DKIM to my domain, I have created a key, added the following to /etc/exim4/conf.d/transport/30_exim4_config_remote_smtp: dkim_domain = mydomain.com dkim_selector = mail1 ...
1
vote
5answers
170 views

What domain name should appear in a DKIM signature?

I followed these instructions to setup OpenDKIM with Postfix, and it works as advertised. My outgoing mails have the DKIM-Signature header added, for example: DKIM-Signature: v=1; a=rsa-sha256; ...
1
vote
3answers
571 views

Wildcard configured emails allow spammers to deliver mail? (SPF: “softfail”)

I have a Google Apps account set up for one of my domains. Wildcard email delivery is enabled on this domain for all emails (ie. anything@domain.com passes emails along to myemail@domain.com), and the ...
1
vote
2answers
3k views

How do I enter a strong (long) DKIM key into DNS?

I'm trying to enter a 4028 bit DKIM key into DNS and it seems that I'm exceeding both the UDP 512 byte limit and also the maximum record size for a TXT record. How does someone properly create a ...
1
vote
1answer
1k views

How to add DKIM feature to the IIS 7.5 - Windows Server 2008 - DomainKeys Identified Mail

How to add DKIM feature to the IIS 7.5 - Windows Server 2008 DomainKeys Identified Mail
1
vote
3answers
2k views

dkim-filter key retrieval failed

I've set up dkim-filter on my mail server. I've set up postfix to use dkim-filter as the milter; However, I'm getting the following in my logs: Jul 7 13:00:29 magni postfix/smtpd[6742]: connect ...
1
vote
3answers
39 views

Is it safe to use port25 to generate DKIM key

I found this site. But if I use it, doesn't it mean that port25.com would know and be able to use my private key?
1
vote
1answer
3k views

How to setup X-SID , X-AUTH & X-DKIM at windows server 2008 r2 with IIS 7.5

I am very sad that my legit emails drops to spam box while i receive many spam emails into my inbox. I very rarely send announcement emails to my all registered members (over 400k right now) but most ...
1
vote
3answers
330 views

Should DKIM signing happen in the application or the MTA?

I'm trying to weigh up whether DKIM signing should be done by the application sending mail (for instance, the mailing list software you're using) or at the mail transfer agent (sendmail, postfix etc). ...
1
vote
1answer
40 views

spf and dkim records in the same dns zone file

I am trying to set up a mail server which will sign outgoing messages with a dkim signature. Part of that process is to set up a dns record for my senders domain with the public key of the key used ...