• by Loren McDonald , Op-Ed Contributor, September 11, 2008

My last Email Insider column ("Email Industry Disagreements: Where Do You Stand?" ) touched off the start of some good debate over single vs. double opt-in (also called confirmed opt-in) that went beyond the usual arguments (list size vs. list quality).

Some readers commented that while double opt-in (DOI) is the better choice, a sizable group of marketers choose single opt-in anyway, along with other practices, such as prechecked boxes and not removing inactives. Others suggested claims that double opt-in can boost deliverability could be overblown.

On top of that conversation, two incidents involving bogus opt-ins make it look as if a perfect storm is brewing, one that makes the case for double opt-in even stronger:

First, columnist Ken Magill exposed how easy it would be for political candidates such as Barack Obama and John McCain (neither of whom uses DOI) to add lots of unwanted email addresses by using single opt-in.

Although he used a genuine email address, his stunt illustrated how easy it is to forge someone else's information on opt-in forms. Read about it here and the mixed reaction it drew at Laura Atkins' "Word to the Wise" blog.

A potentially more damaging incident surfaced with SpamZa, an email revenge "service" that lets you sign up anyone's address, resulting in, presumably, a flood of daily email newsletters.

Most vulnerable to this scheme are high-profile, consumer-focused newsletters that don't use double opt-in to weed out malicious subscriptions, making them increasingly exposed to more unsubscribes, bad addresses and spam complaints.

Arguments Against Double Opt-in

The arguments I have heard against moving from single to double opt-in are these:

· DOI lists are smaller because confirmation emails get overlooked or lost in spam filters

· Deliverability improvements from DOI are negligible.

· Some marketers say the ROI is higher on a nonconfirmed list - presumably due to a larger list and fewer acquisition dollars being wasted.

Arguments for Double Opt-in

I believe DOI neutralizes the two problems I listed above with SpamZa and the political campaigns, but some of the most commonly cited pro-DOI arguments include these:

· It reduces or eliminates bogus email addresses people use to sign up for white papers, downloads or other incentives.

· It eliminates the SpamZa effect, stopping people from hijacking your email list to sign up people they don't like.

· Most ISPs recommend DOI/COI.

· A key benefit is the confirmation record should you need to prove to an ISP or network administrator that an angry subscriber actually did opt in.

· Responsiveness will be higher overall, because only people who want to be on your list will confirm their requests.

· It minimizes future spam complaints and unsubscribes, as the confirmation process eliminates many of the subscribers who have buyers' remorse after hitting "submit."

· Optimizing your confirmation process will minimize the number of emails being trapped in spam filters.

The Smaller-List Argument

The biggest argument against DOI is typically that it will result in a smaller list, with confirmation rates, according to a MarketingSherpa study, being between 70 and 80 percent.

So yes, out of the gate, a SOI list will be larger. But what about after your first few emails? What percentage of this difference is lost after the malicious, input errors, etc. addresses in the first mailing? What about the people who get buyer's remorse after the first one or two emails and hit the spam button or unsubscribe?

What about potential blocking or filtering because some spam-trap email addresses were submitted? Finally, what about potentially improved responsiveness from those acquired via the DOI process?

Now, explain to me again why more marketers aren't switching.

Optimizing the Confirmation Process

To reduce the potential for lost or ignored confirmation emails, try these tips:

1. Explain the confirmation process on the opt-in page.

2. Make sure your "from" line is well branded and easily recognizable and consistent with what someone would expect.

3. Use a simple subject line, repeating the newsletter name and the confirmation request.

4. Use text or HTML with no or minimal images or tables, etc. to ensure good rendering on PCs and mobile devices and minimize potential spam filtering.

5. Test the confirmation process frequently to make sure it works and to see where confirmation emails end up.

6. Try to eliminate input errors on your opt-in forms by using scripts that detect typing errors in domain names (missing @ , aol.cmo, etc.).

The arguments for DOI are pretty compelling to me, but perhaps I'm overlooking some issues. If you have hard facts or tests, including deliverability and response rates, that prove (at least on house lists) that SOI delivers better long-term ROI and lifetime customer value, I would love to see them.

Until next time, take it up a notch.