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Questions tagged [dkim]

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 key retrieved from DNS.

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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 so ...
40
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6answers
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Is it becoming impossible to be a small mail provider?

I operate a small mail server for my private emails, some friends who have websites and two NGOs. In total my server sends between 60 and 400 messages a day. Now a lot of these emails are personal ...
39
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4answers
28k 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 ...
27
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3answers
25k 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 ...
27
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4answers
34k views

Find DKIM and DMARC Records?

Is there a method to find a domain's DKIM and DMARC records using dig or nslookup? I have attempted to do the following: dig somedomain.org any returns many records, but not the known DKIM and ...
18
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3answers
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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 ...
15
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5answers
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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 ...
14
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6answers
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Domain Key not showing up in DNS query

*SOLVED - See bottom of this post * So problem here is that I have been trying to set up a domain key for several days. I've done it successfully in the past, but I just can't get it to work this ...
11
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2answers
4k 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 ...
10
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3answers
18k 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" ...
10
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1answer
1k 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 ...
9
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2answers
6k views

Mail with DKIM Signature gets T_DKIM_INVALID flag by SpamAssassin

I've installed a Debian (jessie) box with postfix and spamassassin. Configured and everything works fine. Except receiving mails with DKIM signatur will produce a flag T_DKIM_INVALID even if the ...
9
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2answers
7k 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 ...
9
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2answers
906 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 ...
8
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1answer
3k views

DKIM: Can I use a RSA key larger than 2048bit, i.e. 4096?

I wonder if I can simply use a 4096bit RSA key for DKIM (in DNS TXT Record). Are there any downsides (neglecting computational effort)? Maybe there are mail servers which can't handle a key this large?...
8
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1answer
15k 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 ...
8
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1answer
8k views

OpenDKIM not signing outgoing mail

I'm trying to setup OpenDKIM on my mailserver running Debian and Postfix. This is the configuration I've done: Generated two keys (for two domains I need to send mail for) Configured KeyTable, ...
7
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4answers
3k 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 ...
7
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4answers
13k 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?
7
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2answers
250 views

Hosting DKIM records on a separate nameservers

For organization we setup a _domainkey.domain.com as a separate zone instead of creating all our DKIM records on our root domain zone domain.com. As a result the nameservers for _domainkey.domain.com ...
7
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3answers
2k 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 DKIM-...
7
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3answers
22k views

no signing table match in OpenDKIM

I have OpenDKIM installed on CentOS. I am using postfix as MTA and dovecot for IMAP/POP3. Now the problem is am trying to setup DKIM for my domain. The mails are send from a sub domain mail.example....
7
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3answers
1k 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 ...
7
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3answers
3k views

Exim4 does not add DKIM signature

Have spent 2 days trying to tell Exim to add DKIM signatures on my Debian8 server. No success. Have read many how-tos, forums but none of possible solutions wotk on my server. Have generated the keys:...
7
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4answers
13k 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 I'...
7
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1answer
11k 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 ...
7
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3answers
2k views

Should DKIM selector names be unguessable?

The M³WAAG DKIM Key Rotation Best Practices document (pdf) recommends a "sufficiently" random DKIM selector name so that it cannot be guessed by browsing the DNS. A literal quotation: 4.3 Key ...
6
votes
1answer
16k 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 ...
6
votes
2answers
8k views

postfix: connect to Milter service inet:127.0.0.1:8891: Connection refused

I noticed that there is a error with milter if I type service postfix status : Jul 01 17:39:01 mail postfix/cleanup[13921]: warning: connect to Milter service inet:127.0.0.1:8891: Connection refused ...
6
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2answers
7k 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
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1answer
5k views

What does dis=NONE mean in an email's Authentication-Results header?

The following is from an email I received recently: Authentication-Results: mx.google.com; spf=neutral; dkim=pass header.i=@yahoo.com; dmarc=pass (p=REJECT dis=NONE) header.from=...
6
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1answer
4k views

DKIM not signing with alias addresses - not internal, not authenticated

I have postfix, dovecot, opendkim and postsrsd installed. I am trying to forward mail from alias@example.com to myemail@gmail.com, and have them signed with DKIM. I use postsrsd in order for the SPF ...
6
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2answers
4k 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 ...
6
votes
1answer
5k views

Exim doesn't want to do DKIM signing correctly

I'm using exim 4.82 on Debian sid. I've followed several tutorials on how to configure exim to sign outgoing emails, but it seems like something is not behaving as it should be. My diagnosis is that $...
6
votes
3answers
7k 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 ...
6
votes
3answers
1k views

Why is my opendmarc failing pretty much everything that comes through?

I have this domain for which I set up SPF, DKIM, and DMARC stuff. Let's pretend the domain is example.com which has the following entries in its DNS zone: example.com. 600 IN MX ...
6
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2answers
836 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 ...
5
votes
3answers
4k 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 that ...
5
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2answers
4k views

Why do I need to escape ; with \ in a DNS DKIM record?

I'm setting up Email Authentication on our domain to allow authentication with our Email Service Provider. My understanding is that the DNS record needs to have any ; escaped, e.g., \; I just want ...
5
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2answers
6k views

Receiving DMARC reports for emails I do not send

I am hosting the email for my domain (lets call it example.com) on google apps (free legacy edition). I recently enabled the DMARC reports so I now get a daily report for the emails sent from my ...
5
votes
1answer
9k 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 ...
5
votes
3answers
2k views

Migrating Email Providers; Are Multiple DKIM Records Viable During Transition?

I am currently gathering requirements for a small (hopefully) project of migrating from SendGrid to Mandrill as a transactional email service provider. We have been using SendGrid for close to 3-4 ...
5
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3answers
2k 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 ...
5
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3answers
7k views

SPF + DKIM + DMARC with Gmail account and external mail server

I,m using gmail with own domain (Google Apps) for my project. Now I want to add external mail server for sending notifications for users. Gmail doesn't give private keys for DKIM and if keys will be ...
5
votes
1answer
617 views

NOT receiving DMARC reports from AOL / HOTMAIL / MSN / OUTLOOK / LIVE

My DMARC DNS record looks like this: (domain name is redacted) _dmarc.domain.com TXT "v=DMARC1; p=none; sp=none; rua=mailto:dmarc@domain.com; ruf=mailto:dmarc@domain.com; rf=afrf; pct=100; ri=...
4
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2answers
625 views

When DKIM is installed, will I still be able to send email for my domain from gmail?

Let's say I own example.com, that I install and configure dkim on my server (apt-get install opendkim opendkim-tools, etc.), and that I add the relevant public key to the domain's DNS records. Then ...
4
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1answer
1k views

DKIM: 'not authenticated' but 'verification successful'

A question if this is normal DKIM behaviour. When sending an email from mydomain it adds it with a signature, and it looks good. But when receiving an email from outside, say outlook.com, i get below: ...
4
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3answers
1k views

DMARC Alignment: Enforce messages pass BOTH SPF and DKIM

Is there a way to enforce DMARC to fail/reject mail that doesn't pass BOTH DKIM and SPF? We have been narrowing the number that are failing, but there are some domains in our aggregate (rua) report ...
4
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3answers
11k views

Postfix - Opendkim - Unable to connect to local socket

I am getting denied errors when postfix tries to connect to the unix socket for opendkim, actual error: Sep 24 15:41:43 service-a-4 postfix/cleanup[17414]: warning: connect to Milter service unix:var/...
4
votes
1answer
7k views

DKIM on postfix relay server

I have a postfix/amavis relay server, with the domain name mail.example.com. It will be a relay for dozens of VPS's, which will have domains like hostname.example.net. So i have actually two ...