·    Frequency/Cadence: 20 emails in 20 days, even from a well-known and trusted brand (my own recent experience), is probably too much for many subscribers, who might get fed up and choose the spam button over the unsubscribe link.

·    Relevance: If that same company sends only three targeted and highly relevant emails monthly, but the consumer simply wants out, he might choose the unsubscribe over the spam button.

·    Trust: Is your brand highly trusted regardless of channel? If not, or its trustworthiness is questionable, you will likely have a tough time getting people to hit the unsubscribe link over spam-complaint button.

·    List Composition: A B2B list typically sees fewer spam complaints because the report-spam button is an infrequent option. On the other hand, the spam button is more prevalent in some Web mail clients than others.

·    Ease to Unsubscribe: How prominent is your unsubscribe link? Is it in tiny, gray font buried among a bunch of boilerplate legalese, or does it stand out easily in your email administrative footer?

Also, if subscribers can't update their email addresses easily, they have no choice but to unsubscribe. Providing alternatives such as reduced frequency, preference updates and address change, greatly increases your chance to retain subscribers and minimize spam complaints.

Stephanie Miller of Return Path suggests an "unsubscribe flip -- offering choices or frequency options." Using this technique, "some of our clients have seen up to 50% retention of those who started out unsubscribing," she adds.

I suggest several ways to approach unsubscribe optimization in a presentation,  "Unsubscribe Alternatives."

Where to Put the Unsubscribe Link?

Everyone seems to agree that your unsubscribe link should be prominent and always included in your email administrative footer. Whether to place it at or near the top of your emails generates more "it depends" answers than disagreements among industry experts.

Consider these general guidelines for placing a second unsubscribe link at the top of your emails:

·    High Complaint Rate at Specific ISPs: If you see higher-than-average spam-complaint rates at a specific ISP, then consider adding the additional unsubscribe link at the top of emails sent to those subscribers.

·    Locate Preference Links at Top: If you have low complaint rates, consider locating your "Change Address" and "Update Preference" links near the top of your emails, but below your teaser copy and calls to action.

·    Inactive Subscribers: If you are segmenting out your inactive subscribers, definitely put an additional unsubscribe link at the top of the emails sent to those subscribers.

·    List Source: If you utilize aggressive opt-in practices such as co-reg, sweepstakes opt-ins, etc., consider putting an unsubscribe link near the top of your emails for those particularly problematic lists, suggests Chad White of Smith-Harmon and the Retail Email Blog. "Do that for a little while, and then migrate them over to your main file after they've become engaged," he says.

·    Test: As always, experiment and test different approaches until you find what works best for your situation.