BarNet Documenation

Blocked email report

BarNet users now enjoy the benefits of a daily report of blocked email. Each morning you will receive an email with a list of addresses that have attempted to send mail to you which has been rejected by our systems.

BarNet uses a wide range of email verification techniques and procedures. There are a number of reasons why mail is temporary blocked or rejected by us. A brief explanation of the main blocking reasons is set out below.

If there is mail that is included in the temporary blocked list of your report and you are confident is legitimate mail you may choose to unblock the mail by clicking on the link in the report.  This will allow subsequent attempts to send to you from that address to pass through our systems.

If anything is unclear you can email us at info@barnet.com.au or you can call the BarNet support line on 02 8815 9090.

Blocking Reason Failure Type What happened Why this happens
Greylisting Temporary The first time an email is send to you from that email address we reject the first delivery attempt to ensure that the other side is a valid MTA Zombie-computers don't retry failed email
Unverified address Temporary The email address the mail is coming from hasn't been validated yet Zombie-computers often mail from made-up email addresses
Temporary lookup failure Temporary The DNS servers for the sender email address are unreachable Badly configured DNS servers, bad network connectivity
Undeliverable sender address Permanent The email address of the sender is not valid It's a made up email address
Unknown sender domain Temporary The email address of the sender is not valid It's a made up email address
Relaying denied Permanent Email for an unknown domain ended up at our mail server This shouldn't show up
Unknown recipient Permanent The destination email address didn't exist This shouldn't show up
Blacklisted Permanent The sending MTA comes from an IP address which is blacklisted by various RBL The sending computer is a zombie-computer.
Access denied Permanent This email is blocked due to your personal blacklists  
Message Size too large Permanent The email is too big The email is too big
VRFY: Unknown recipient Permanent The remote MTA is trying to find out if a certain email address exists This shouldn't show up
Server configuration problem Temporary Something went wrong on the mail server This shouldn't show up
Unknown recipient domain Permanent The remote MTA is trying to find out if a certain email address exists This shouldn't show up
Malformed DNS server reply Temporary There is a problem with the DNS answer A configuration issue with the senders DNS server

What is what?

  • DNS - Domain Name Server, the address book of the internet.
  • MTA - Mail Transfer Agent, the software sending and receiving emails on mailservers.
  • Zombie-computers - Computers sending out unsolicited commercial email or email viruses.
  • RBL - Realtime Black List, a server which gives data about machines on the internet known to be zombie-computers.
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