The process of gradually increasing the volume of emails sent from a new or inactive email account to build a positive sender reputation and improve email deliverability. This method involves sending a small number of emails initially and progressively raising the volume while ensuring high engagement and low bounce rates. The warm up process usually mimics human-like behavior (exchanging emails between two friends or colleagues). The goal of email warm-up is to establish trust with email service providers (ESPs) and email filters, preventing emails from being marked as spam. By slowly scaling up email sends and monitoring interactions such as opens, clicks, and replies, senders can demonstrate that their emails are legitimate and desired by recipients.