Barracuda's blacklist - keep out

Barracuda Spam Firewall is a popular spam filtering software. One of the ways it figures out whether an email is Spam or not is through the use of its "Intent Engine". The "Intent Engine" is a human run and maintained blacklist which is turned "On" by default with each new Barracuda installation.
To get blacklisted inside the "Intent Engine" you must first have had a complaint submitted to Barracuda by one of its customers. By default Barracuda assumes all mail is good mail, until that initial complaint is filed. Once a complaint is filed, a person will look at your email for three attributes to determine if it belongs on the blacklist.

1. "To:" line cannot be obfuscated. Anyone who uses blind carbon copy line (BCC line) to load up a list of recipients would fail this test.
2. The email must let the recipient know how they got on the email list inside the body of the message.
3. There must be a one-click unsubscribe link.

If the email fails in any of these areas, then the person analyzing the email will add URLs that are linked to in the email to the blacklist which means that future emails sent by that sender could be blocked. Once your URL gets on the blacklist, any Barracuda customer who has the "Intent Engine" turned on will likely not receive your messages.

We encourage our customers to add a quick one-line explanation to the body of their messages that explain how and where permission was gained from the customer to be on your list. This line can be in the header or the footer of the message. Not only would this help with deliverability, but it would also help make transparent your relationship with the end recipient which is always a good thing.

source: Campaigner
read more: Barracuda Lookup