Scammer try to trigger emotional responses, such as anger, shock, sympathy, panic, curiosity, etc. By doing so, they are more likely to deceive their targets.
For example, they may send you emails on the following topics:
An incredible deal/discount on products.
Winning a high-value lottery.
Job offers.
Unauthorize access to your account.
In the event of disclosure of your confidential data.
Free credit reports.
A (fake) purchase from your account.
Fundraising campaign for the poor suffering from rare diseases/victims of natural calamities.
There are many topics to which email recipients react emotionally. Hackers know this and will use e-mail subject lines that encourage targets to take action without properly inspecting or investigating the e-mails, and will try to respond promptly.
Hackers like to create a sense of urgency. Sometimes, scammers set time limits to force users to act quickly in a panic. Oftentimes, hackers set a deadline of 24 or 48 hours. Such deadlines put pressure on user to take the immediate actions suggested in the email.