。
Please be careful of spoofed emails.
Literal
Spoofed emails [to-に] please-be-careful.
騙り (かたり) means 'impersonation, spoofing' — from 騙る ('to deceive by pretending to be someone else'). ご注意ください is the polite imperative using the お/ご~ください pattern. A standard public-service warning format, concise and formal.