False-Positive A false-positive results when Brightmail believes that a message is spam when it in fact is not spam.
I eventually found this FAQ about Symantec's blocking.
Here are their suggestions - none of which apply to me! Check if your sending IP is on any spam lists, search for “spam database lookup”.
Last year, while trying to buy a house, Symantec's Message Labs decided to block my Estate Agent and my bank from receiving any emails from my personal domain.
In the middle of a rather stressful house purchase, I had to swap my email addresses and convince the parties involved to all to use the new one. Every so often - usually when I want to email a large company - I get the following NDR Delivery to the following recipient failed permanently: [email protected] Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the server for the recipient domain by cluster8 The error that the other server returned was: 553-Message filtered.
IMT recommends that you do not set up email filtering rules for these messages.