A bounce is an email whose delivery was rejected by the recipient's mail server. The reason an email is rejected for delivery determines if that bounce is considered "hard" or "soft". You'll notice these in the Activity Feed and email reports.
Hard bounces vs. soft bounces
A hard bounce occurs when the email has been permanently rejected either because the email address is:
- invalid; or
- doesn’t exist.
We automatically prevent recipients that hard bounce from receiving future emails (i.e. they are unsubscribed). We do this to ensure that your sender reputation remains high. Continuing to try to send to someone with a known bad address will harm your sender reputation, which affects how likely your email is to end up in someone's inbox.
A soft bounce means that the email address was valid and the email reached the recipient’s mail server. However, it bounced back because the:
- mailbox was full (the user is over their quota);
- server was down; or
- email was too large for the recipient’s inbox.
"Blocks" are also treated as soft bounces because they are less permanent than a hard bounce. Blocks occur when your IP address has been added to a blacklist or has been blocked by an ISP or messaging organization. Typically it is possible to have your IP address removed from a block list, and some lists automatically do this after a period of time. If you are experiencing blocks please get in touch with our support team who will be able to assist you.
Sometimes when we attempt to deliver mail we receive what's called a "deferral" from the recipient's mail server. This means that the recipient's mail server has temporarily refused delivery of an email. If this occurs, we will attempt to send the email for up to 72 hours until it is delivered. If the email still cannot be delivered over the 72 hour period, it will be considered a soft bounce. Learn more about deferrals.
Can I re-enable email permission for a contact that hard bounced, so they can receive email again?
Yes, you can do this by going to the contact and following the steps demonstrated below:
Please use caution when doing this; as noted above continually emailing people who have previously hard bounced will affect your sender reputation. This should generally only be done in the case where you had an incorrect email address for a contact and have corrected it.
How are out of office replies treated?
We don't treat out of office responses any differently. They show as "delivered".
Note that some email distribution lists (e.g. Office 365) don't receive auto replies.