Bleeping Computer
Scammers use fake ‘unsubscribe’ spam emails to confirm valid email accounts to be used in future phishing and spam campaigns.
For some time, spammers have been sending emails that simply ask if you wish to unsubscribe or subscribe. These emails do not explain what you are unsubscribing or subscribing to and are being used by spammers to verify if the recipient’s email is valid and susceptible to phishing scams and other malicious activity.
The “confirmation” emails use mail subjects, such as “We_need your confirmation asap”, “Request , please confirm your unsubscription”, and “Verification.”
The email messages are very basic, with just colorful boxes containing links asking whether you would like to unsubscribe or subscribe, as shown below.