The term 'Thoughtless Sender of Emails' can be summarized as a Spambot, which is a 7 letter word. A Spambot is a computer program that is designed to send out large amounts of spam emails. These emails are usually sent out without any consideration for the recipient, hence the term 'Thoughtless Sender of Emails'. Spambots are often used by malicious actors to spread malware or phishing links, and can be a nuisance to email users.