Catalog Request Spam
Google ReCaptcha protects all forms from spam, effectiveness varies on the sophistication of the spammer:
Requiring an email address on submission can help mitigate spam but again is not a panacea. See Admin > Management > Settings > Catalog > Require Email?
The catalog request form can be disabled under rampant spam abuse. See Admin > Management > Settings > Catalog > Enable Catalog Request Page?
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