By Matt Blumberg
CEO & Chairman
Late last week, well-known investor and blogger Fred Wilson posted an article about updates to the Zemanta content recommendation tool. “Now,” Fred wrote, “if you have the Zemanta extension installed, when you go to gmail or yahoo mail, you’ll see a button that says Zemanta that lets you use the content recommendation service while composing an email.”
One of his readers, writing as BmoreWire, asked how those “pictures and recommended links affect the message’s delivery in spam filter algorithms” — so Fred asked us to weigh in. (Disclosure: Fred is an investor in both Zemanta and Return Path.)
As always, the answer is that it varies. Some spam filters pay a lot of attention to links or pictures in the message, while others mostly ignore it. The last time we studied it somewhat scientifically, link reputation impacted deliverability about 6% of the time, as compared with IP reputation at 77% and other content at 17%.
In most ISP situations, the reputation of the “last hop” IP address is considered before any content filter is applied. When sending via Gmail or Yahoo!, you inherit their reputations. But if you tried to implement this in emails sent from your own system, the emails would arrive with your reputation (which, by the way, you can check at senderscore.org.)
Once the message gets past the reputation system and into the content filter, the links in the message — whether a hyperlink to another site, or a reference to an image — begin to matter. To prevent phishing attacks, many systems take notice when a brand-new URL starts coming from a whole lot of different places, or is sent out by a whole lot of different users on their system. This isn’t guaranteed to be a problem, but it’s considered suspicious and could easily result in temporary delivery delays, even when you’re sending the mail out through a major ISP.
The other issue to keep in mind is that, by default, most email clients (either on the web or on the desktop) don’t show images by default. If you’ve looked at much spam, you’ll quickly understand why.
Overall, our advice would be the same it is everywhere else in email: be careful what you send to whom. Don’t send random content to people who aren’t expecting it from you, and you’ll probably be okay. If you use Zemanta to include content from generally trustworthy sources like Wikipedia or Flickr (which appear to be where most of their pictures come from), then it’s probably not going to affect the delivery of your emails. But if your message wouldn’t be interesting enough on its own, without help from Zemanta, don’t hit send.