Glossary

List-unsubscribe is an optional process included in the email header, enabling subscribers to opt out of an email list without clicking on an unsubscribe link. At Mailgun, we always recommend providing subscribers an option to stop receiving emails, so they don’t mark emails as spam. If they do, it can tank a domain’s reputation and email deliverability.

Looping mail is the unintentional process of autoresponders sending automatic replies that end up in a loop. For example, if a company sends an email to its customer but the customer has an  autoresponder set up, it will send an automated reply to the brand. But, if the brand also has an auto-reply on, the automated replies will continue responding to each other. This infinite exchange of automatic responses creates an email loop. While email automation has many benefits, an automated response loop can occur if brands set up automation incorrectly.