The CBL - Composite Blocking List

My Provider is blocking me!

The CBL is specifically intended to be used to filter email coming into a mail server from the Internet, not to filter email going out to the Internet.

In "tech-jargon", it's intended to be used on email going to the MX for your domain, NOT to block your (or your user's) access to a "outbound SMTP server".

This most often happens when the user is "roaming" (especially via wireless), and is attempting to send their outbound email through their regular "non-wireless provider" and their provider is using the CBL. But it can happen when a service similar to iPowerWeb (an Email Service Provider, "ESP") uses the CBL.

If this happens you can't send any email at all!

This is UNSUPPORTED use of the CBL. We STRONGLY discourage ESPs and other providers using the CBL to block their own users trying to send email to the Internet.

It's just plain silly and unnecessary.

If you're a end-user, provide the following text to your provider. If you're the provider, pay VERY close attention to it.

We're getting a lot of reports of spurious blocking caused by sites using the CBL to block authenticated access to smarthosts / outgoing mail servers. THE CBL is only designed to be used on INCOMING mail, i.e. on the hosts that your MX records point to.

If you use the same hosts for incoming mail and smarthosting, then you should always ensure that you exempt authenticated clients from CBL checks, just as you would for dynamic/dialup blocklists.

Another way of putting this is: "Do not use the CBL to block your own users".

Continued failure to apply the CBL properly MAY result in the CBL revoking permission for you to use the CBL.

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