We cover an explanation of DKIM Email Authentication in our blog entry DKIM Email Authentication. Here we’ll summarize some the top advantages and disadvantages.
DKIM Authentication – Advantages
If you have a very large list, your campaigns are more likely to get blocked or “throttled” by major ISPs like AOL, Yahoo, Hotmail, and Gmail. However, if you are using DKIM authentication, (or if your ESP is doing DKIM signing), the throttling limits are often raised by some domains.
Potentially less stringent SPAM filtering. If you send marketing messages, email firewalls can be harsh when they scan your content. For example, if you have a large number of email subscribers that are all in the same domain, then sending a campaign to that list is going to look like a wave of spam. Again, authentication (and maybe some email certification) may smooth things out a bit.
Not too long ago, Bellsouth started blocking HTML emails randomly (no idea why – perhaps a Bellsouth employee can enlighten us?) Interestingly, since Pinpointe authenticates all of our customers’ emails by default, our emails seemed to get through just fine.
One thing to keep in mind however is that authentication (and authorization) do not give you a free license to start creating and sending spammy, low value email content. Your content is still going to get filtered. Authentication and authorization help receiving systems to know, with absolute assurance, that you are who you say you are.
DKIM Authentication – Disadvantages
Authentication has a few minor drawbacks worth noting. These are relatively minor and only occur in edge cases, but for full disclosure – here are the downsides:
If you are using an ESP who is doing DKIM signing, you “might” see this scenario. Depending on the email software being used by the recipient, your email may be displayed to some recipients as follows:
Sent from mail.pinpointe.com on behalf of firstname.lastname@example.org
For most people, that’s not a big deal – but the receiving email might be displayed like this.
Authenticated emails can occasionally get rejected by mobile devices if the email is forwarded. Here’s the scenario. You send an authenticated email to your customer account. The message’s authentication says, “this message is only authentic if it came from Pinpointe Server [server-name],” but the recipient forwards the message from his company account to his Blackberry. The Blackberry server receives your message, but since it was forwarded from your recipient’s company server, it appears to be a forgery when they read the authentication instructions.
The bottom line is this: if you have a big list (tens of thousands), you should be working with your ESP to do authentication and authorization to help improve email delivery. If your list is relatively small (in the hundreds) then you probably don’t need it yet – but start getting yourself educated on the topic.