A feedback loop is a service offered by some internet service providers that reports back complaints (when a subscriber hits the spam or junk button in their inbox) to senders. It’s provided to aid senders in keeping a clean list. Most providers let an email's return path manage it for them. Feedback loop complaints are automatically unsubscribed in Engage.
A hard bounce happens when, for a reason that appears to be permanent, Salsa Engage cannot deliver an email. Hard bounced emails are automatically unsubscribed. Following are few reasons an email address may hard bounce:
- The recipient email address does not exist.
- The domain name does not exist.
NOTE: there are times when a valid email address can bounce or a subscriber could mistakenly unsubscribe or mark you as spam. The supporter needs to go through your an Activity form signup process with the same email to resubscribe back into your list.
A soft bounce happens when there is an apparently temporary delivery issue that prevents Salsa Engage from delivering an email. Salsa Engage handles these differently from hard bounces. Salsa Engage continues to try to deliver soft bounced emails several times, and the emails are not removed from future mailings unless delivery has failed four times in a row. Once an email has soft bounced four times, the supporter is unsubscribed. Here are a few of the things that can cause a soft bounce:
- The recipient's mailbox is full (over quota).
- The recipient email server is down or offline.
- The email message is too large. (Email will be returned as non-deliverable but is counted as a soft bounce.)
- The recipient email server has completely blocked delivery.
- Spam filtering. To avoid this, you should ask your supporters to whitelist SalsaLabs.org.