Get email through even though client's hosting mailserver is blacklisted

[the_griz]

More and more companies are getting caught up in our blacklist filter because one or more of the blacklists(spamcop, etc.) have caught a hosting services' particular email server and placed it on their blacklist.

It is terribly frustrating to have 10 emails coming from a legitimate client and 2 emails get blocked because they happened to get sent from server142.hosting.com (blacklisted) where as the other 8 went through server143.hosting.com (which is not blacklisted.)

I can't keep telling clients to get reliable and responsible email providers otherwise I won't have any clients left! :-)

Is there a way to have an email domain pass through even though the sending server has been blacklisted? I literally have a dozen or so domains where this happens regularly.

Thanks!
Tom

[Labsy]

Try whitelisting the domains. I do not know which method will work for you:
Improving Anti-spam system - Zimbra :: Wiki
or
Whitelist Domain Name