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What’s the Difference Between a Hard Bounce and a Soft Bounce?


When you send campaigns through Robly, there are four types of bounces that can happen when you send an email:

Hard Bounces:

When an email is rejected by a server because the email does not exist there. These emails are removed and sent to your Unsubscribed list.


Processed as a hard bounce; when an email is sent to a domain that simply doesn’t exist. These emails are removed and sent to your Unsubscribed list.

Soft Bounce:

When an email is sent to a server, gets processed, and for some reason is sent back to Robly. We then get messages like “Server Temporarily Unavailable” and “User Over Quota.” We do not remove these emails from your list unless they soft bounce more than 6 times.


Causes of a deferral include:

  • The receiving server doesn’t recognize the IP, and is afraid you’re sending spam.
  • The receiving server doesn’t have any open ports to receive email.
  • The recipient’s mailbox is full.
  • Some recipients have marked your mail as spam, but not enough for the server to block you. Instead, they will refuse to receive more until they see what the rest of your current recipients do.

    Deferrals are generally temporary; we continue to try to deliver the email for 72 hours.


These are typos in your emails. Check for common typos like the omission of periods or unwanted spaces.

List Cleaning

Robly cleans your list automatically. We take any hard bounce, unsubscribe, and SPAM complaint off your list immediately. If an email address soft bounces more than 6 times, it will automatically be removed from your list.