When the type='submit' button is pressed, a bunch of letters are sent in a row. How can I make sure that only one email is sent?

Question

Fight against spam

I put a google-captcha on the form, but spammers spam manually: they fill in the form fields, fill in the captcha, press the SEND button (type='submit') and not one, but several letters are sent at once. How to deal with it? Thanks

Answer 1

create a table in the database
ip, datetime, md5
in the script, read md5 from several form fields,
check the received hash against the table with the condition, for example, for the last 5 minutes
, if not, then send a letter, add it to the database.