build an anti spam code

[OwenTheSamoan]

I have a website and it is being attacked by spammers trying to trick my members into giving out their personal bank information. I am using mysql with php. I have a message system in my site that they are using to spam the members. I am having a problem with creating a script that would identify the member name of someone that is sending out 100 messages or more with the same exact or simialr message. This is what I have so far but I can't figure out how get it to work wher it identifies 100 or more messages that are identical or simialr. Any help would be greatly appreciate. The fields I am using are "username" and "messages" the table name is "mail"

select distinct messages, username from mail group by messages having count(messages)>200;

Thanks,
OwenTheSamoan

[rehfeld]

could you provide more info?

do you actually allow your members to send emails to all other members?
or is the spammer exploiting your website via sql injection?

you need to provide much more info about how your system works for us to even try and help.