What are the pros and cons of DOI?

The strengths of double opt-in lie in list quality, deliverability, and compliance assurance. Every confirmed subscriber represents a verified email address owned by someone who deliberately clicked to join your list, virtually eliminating typo addresses and bot signups. This verification translates directly into better engagement metrics-DOI lists typically show higher open rates, click rates, and lower unsubscribe and complaint rates because every subscriber actively chose to be there. From a deliverability standpoint, cleaner lists mean fewer bounces and spam trap hits, which helps maintain strong sender reputation with ISPs.

DOI also provides robust compliance benefits. The confirmation click creates a timestamped record that the email address owner affirmatively consented to receive messages-invaluable for GDPR compliance where you must demonstrate consent on request. In jurisdictions like Germany, DOI is effectively the legal standard for proving opt-in consent, and many organizations worldwide adopt it as a best practice that exceeds minimum legal requirements. If a subscriber ever disputes that they signed up, you have clear evidence of their deliberate confirmation action.

The downsides of DOI primarily involve subscriber attrition and operational complexity. Confirmation email non-completion rates typically range from 20-40%, meaning a significant portion of people who initially express interest never finalize their subscription. Confirmation emails can land in spam folders, get overlooked in crowded inboxes, or simply be ignored by users who didn't realize a second step was required. This creates pressure to optimize confirmation email design and consider reminder sequences, adding complexity to your subscription workflow. DOI sacrifices quantity for quality-accepting fewer subscribers in exchange for a more engaged, compliant, and deliverable list.