Currently resolving a WAN virus issue where the domain email is getting blacklist every day.
Whilst getting the WAN safe we're having to delist the domain so genuine emails can flow. I've been using http://cbl.abuseat.org
which has been working fine but today their server appears to under strain and I get "The website is too busy, please try again later." when trying to delist.
Are there any other free services out there which delist your domain/IP from being black listed?
Doesn't make sense to attempt de-listing if you are still in the midst of a cleanup. Some services will re-list you for longer and longer periods for falsifying the application to de-list.
Try MXtoolbox.com to check the most-used RBLs.
Also, move your outbound mail traffic to a different public IP than you use for general internet access.
Then, shut down all SMTP outbound traffic except for an explicit list of your authorized SMTP relays. That way, if your users start pumping out spam, your relays will not get blacklisted.