Single opt-in

Single opt-in is the process of adding a user to an email list with just one step – typically by submitting an email address through a form or popup. After that, the user is immediately added to the mailing list without verifying their email address. 

While this method may seem like a fast way to grow a list, Mailgun strongly recommends against it. Single opt-in increases the risk of fake or mistyped addresses, spam traps, and uninterested recipients, all of which hurt your deliverability.  

Instead, we advocate for a confirmed opt-in (also called double opt-in), where users must click a confirmation link in their inbox to complete signup. This not only validates the address, but also verifies consent, setting you up for stronger engagement and fewer complaints.  

Confirmed opt-in ensures: 

• Better data 
• Fewer bounces 
• Stronger sender reputation 
• Happier subscribers