Same issue here. I’ve already complained on the Symantec forum, along with a dozen of other (small outfit?) administrators. This is a nightmare and goes directly against what an open an transparent internet should be. Google at least is much more descriptive in their refusal messages. Symantec’s servers don’t respond at all, they just time out. This is, according to, yet another unhelpful Symantec employee, because the IP address of the sending mailserver has a bad reputation. Which obviously isn’t the case, it isn’t in their database. This server is being monitored for over a year for several different blacklists and hasn’t been listed, ever. Like others in this comment-thread, I enforce very strict security for users on this server, and it’s low-traffic anyway. Symantec is doing their clients a disservice, but OTOH: it’s the clients themselves that choose Symantec. No, you’re not getting a lot of spam, but unfortunately you’re missing a lot of legit e-mail in the same run.
I’m not sure how this messagelabs.com service works, but it might be cool if we could organize to have outgoing messages from messagelabs.com servers rejected at a large scale.