You received a warning message because you have sent IP or email addresses from the ORF Log Viewer using the Remote Control feature to a list which already has too many items.
Please consider that ORF was designed to rely on automated tests like the DNS Blacklist Test and SURBL Test to catch spam, instead of relying on manual lists. Manual lists require a lot of work to maintain, and you will get little (or no) results by adding the spammer to the blacklist each time a spam slips through filtering. Also, if you add hundreds of entries, it makes the maintenance of these manual lists very difficult.
The same applies to whitelists: if ORF is configured properly, it will rarely block any legitimate emails (if any), so whitelisting senders manually is not required at all. Instead, you should rely on the Auto Sender Whitelist feature, which monitors your outgoing email flow and collects the email addresses of people your users correspond with, so when they reply back, their emails will be automatically whitelisted.
If ORF is configured properly, it will catch about 94-99% of spam emails with no manual interaction required and with no false positives. If your catch rate is well below that, it is recommended to read our best practices guide.