Posted by Virus Bulletin on Sep 19, 2011
Good practice means good performance.
Newsletters that do not confirm their subscriptions are twice as likely to be blocked by spam filters as those that do, Virus Bulletin has found.
The research, in which over 500 newsletters were sent to 21 anti-spam solutions, was part of the most recent VBSpam comparative test. Unbeknownst to participating products, newsletters were divided into those which had confirmed the subscription and those which had not. The filters were twice as likely to block newsletters that did not confirm the subscription.
'Confirmed opt-in', or COI, is considered good practice in the anti-spam industry and in many countries it is illegal to send bulk email without having the subscription confirmed. Still, more than half of the newsletters in the corpus gathered for the VB test did not do so; this research now shows that this is not only bad practice, but it may also lead to bad performance.
Several of the newsletters did use other methods to ensure spammers do not subscribe to their emails, such as the use of CAPTCHAs. However, this does not prevent users from mistyping their addresses and the emails thus ending up in the wrong inbox; recent research showed that each month a very large number of emails end up in the wrong place because of typos in email addresses.