See this help document.
https://www.fastsecurecontactform.com/invalid-input-spam
Many are using the Akismet feature the form and am not having any problem. Try a message other than “test” because I have had it check as spam if you just type “test”. If you continue to have the check return as spam here is more help:
Update to the latest Fast Secure Contact Form and then you will have more Akismet settings to change:
Update: Version: 2.9.4 – 11-Oct-2010
– Added new option for what should happen if Akismet determines the message is spam.
If you select “block spam messages”.
If Akismet determines the message is spam: An error will display “Invalid Input – Spam?” and the form will not send.
If you select “tag as spam and send anyway”.
If Akismet determines the message is spam: The message will send and the subject will begin with “Akismet: Spam”. This way you can have Akismet on and be sure not to miss a message.
Also you can turn off Akismet for the form in the form advanced options. This does not turn off Akismet for the blog comment system.
Even with Akismet turned off you still can have the CAPTCHA protecting against automated spammers.