Possible to prevent SPAM by using ACL?

Hi,

 

 

I am very new to iRule and any help is greatly appreciated.

 

 

I have apache web servers behind F5 and these servers are there to serve as web message clients to send messages from both anonymous users and APIs.

 

 

We had some incidents that Spammers used the webservers to send spam.

 

 

I am trying to see if there could be an iRule written to with deny/access list to prevent or allow users.

 

 

There are around 4500 trusted IPs that I can whitelist. Is there any limitations on iRule before it impacts performance. Or is there a way that external file iRule can look up for those white listed IPs.

 

 

Please let me know your ideas..

 

 

Thanks in advance.