Authenticating your email with DKIM

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Joined: 05 Nov 2003
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PostPosted: Thu May 13, 2010 8:59 pm    Post subject: Authenticating your email with DKIM Reply with quote
I thought I'd post this here as there seem to be a lot of people having problems with rejected emails.

In case you're not aware, DKIM (short for DomainKeys Identified Mail) is a system for authenticating emails sent from your website. If your email has a valid DKIM signature, then it's less likely to be rejected by spam filters.

There's an open-source PHP implementation of DKIM available from SourceForge. You can download it here.

The package includes a README.html file with instructions on how to set things up, although step 2 is missing a bit — to generate the public key from your private key, enter this line at your command prompt:
openssl rsa -in key.priv -pubout

After you've uploaded the files to your server, I strongly recommend you change the permissions of dkim-cfg.php to 0400 to protect your private key. (Although this will only work if you're using PHP-CGI or PHP-FCGI.)

The next step is to add the public key to your site's DNS records. If you set $DKIM_s equal to 'contact' in dkim-cfg.pgp, then you'll need to add a TXT record with HOST set to 'contact._domainkey'. The data part can be obtained by calling BuildDNSTXTRR(). While you're editing the DNS records, I suggest you also add an SPF record if you haven't already done so (although this isn't a requirement for getting DKIM up and running).

You might need to wait a while for the DNS system to update itself before you can authenticate emails successfully. If you send one to then it will send back a reply telling you how you got on. (Don't forget to add a "From" header containing a valid email address at your domain, otherwise you won't receive anything.)

I hope this helps.
Phil Ronan
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Joined: 16 Mar 2001
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Location: Stroud,Gloucestershire

PostPosted: Fri May 14, 2010 7:27 pm    Post subject: Reply with quote
Interesting post

We do have a new smtp setup being worked on and hopefully rolled out soon, which will allow you to use DKIM signing on outgoing smtp mail, it will be setup on request not as standard, as like you say it needs changes to dns records and will need private/public keys being made on the smtp servers accordingly.

Maybe worth if anyone does use this and in the future would like the DKIM signing on their SMTP to keep a local copy of your private keys as we would need a copy of this to avoid you making changes to your DNS records should you want this.
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PostPosted: Tue Jan 10, 2017 9:23 am    Post subject: Reply with quote
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