According to the website

statista.com, $28\mathrm{.}5\%$ of all email traffic in $2019$ was made up of spam $-$ those pesky, useless, and potentially dangerous messages that just clog our email inboxes. Most email servers these days can filter spam automatically. Spam messages often have certain suspicious phrases in the subject lines. For example, "You Have Been Selected" is one such phrase.

An incoming email is checked for key elements, such as this phrase, then the server decides whether to put the email in your mailbox or send it to the spam folder.