A sign-up flow where the subscriber confirms their email address by clicking a link before being added to the list.
Definition
Double opt-in (DOI) requires a new subscriber to confirm their email by clicking a link in a confirmation email before they're added to the marketing list. Single opt-in (SOI) adds them immediately without confirmation.
Double opt-in costs you signups (typically 20–30% never confirm) but produces a higher-quality list with better engagement rates and lower bounce rates — which protects sender reputation. In some jurisdictions (e.g. Germany), double opt-in is legally required.
How Wizel handles it
Wizel writes the confirmation email itself — branded, clear CTA, on-tone — so the DOI confirmation rate stays high. The default 'click to confirm' email from most ESPs converts poorly.
Related terms
Email deliverability
Whether your email actually lands in the inbox vs the spam folder, promotions tab, or nowhere at all.
List hygiene
The practice of removing unengaged, bounced, or invalid contacts from your email list to protect deliverability.
Transactional vs marketing email
Transactional emails confirm an action (order, password reset); marketing emails promote products or content. Different rules, different lists.
Last updated 2026-04-30
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