jabn

Looking at USPS Web Tools now.

Because they will receive a free product. That's why they are doing what their doing to receive multiple freebees.

Please reread my comment. I'm talking "Mailing" address. Anyone can have multiple email addresses. so doing what you're saying still wont stop somebody from adding spaces to the "Mailing address. Email address yes but not "Mailing" Address. I see what you're saying about the email confirmation but they can create another email adress and add spaces to their mailing address. When they do this the problem still exists.

Yes that's good but the other issue is the mailing address. They could create multiple email addresses and verify that it exists. The mailing address is another issue. They can for example use 111 mailing address ave as 111 ma iling address a v e, 1 1 1 mailing address ave etc. and not be considered a duplicate.

I'm thinking of grabing their IP and store it in the DB. Then check for IP duplicates. Then they can change their mailing address and email all they want. The only way around that is to fill out the form at a different IP. Does anyone think that's a bad idea?

Yes

I have a form with PHP validation and also a mysqli query checking for duplicates in the database for mailing address and email address in mysql. It works fine but the customers are adding spaces in the mailing address for example 111 mailing address A V E, 1 1 1 ma iling address A V E etc. and my sql query doesn't see that as an address that's a duplicate. Their alslo adding email address like my@emailaddress.com and m.y@emailaddress.com, m.y.2@emailaddress.com etc to bypass that comparision also. Is there anyway to stop this from happening?