The Email Bounced Back to the Sender

The sender received an error from our system saying an email wasn’t delivered for one of the following reasons:

1. Address does not exist

How to fix it:

  • The sender typed your email address incorrectly – ask them to double check the address they used
  • The sender has the wrong email address stored in their auto complete – tell them to update their address book or cache
  • You set-up your email software (e.g. Outlook) with a typo in the reply address - so when the person you emailed replies to your emails, it goes to the wrong address
  • The email address they are sending to was recently added to Zimbra but it’s still bouncing. This is almost certainly caused by a caching issue – tell the sender to try again in one hour

2. User over quota

How to Fix it:

  • The sender received a bounce back stating that your mailbox is over quota – increase your mailbox storage quota or delete some emails from your mailbox

3. Sender’s email was rejected as spam or because it contained a virus or disallowed attachment

How to Fix it:

  • The sender will have received a bounce back message stating that our filtering system blocked the email. The email may have been placed in the quarantine and may be able to be released by your email administrator (whether this is possible or not depends upon the settings for your email domain which are controlled by your email administrator).
  • If the message was blocked because we considered it spam - ask the user to resend the message using plain text format, and ask them to write a proper subject line, so that the system is less likely to consider the message to be spam. Alternatively, ask your email administrator to white list the senders email address.
  • See Common problems with Spam and Virus filtering settings for more details

Useful Links:

Why are emails to new email addresses I just set-up still bouncing?

The Email Didn’t Bounce Back to Sender, but it hasn’t Arrived

How to Flush your Local DNS Resolvers Cache