Compliance
Single Opt-In
A subscription process where users are added to a list immediately after submitting their email, without confirmation.
Definition
Single opt-in is a subscription process where users are added to an email list immediately after submitting their address, without requiring confirmation. While faster and simpler than double opt-in, it risks invalid addresses, typos, and malicious signups. Single opt-in lists typically have higher bounce and complaint rates.
Pro Tip
If using single opt-in, verify email addresses at signup with real-time email verification.