It's important to establish a good sender reputation before adopting a new domain or IP address, and email warm-up is the commonly used procedure to achieve this.
To begin, send emails to "warm" contacts like friends, family, and co-workers, and check if they read, respond, or mark them as important if they land in the spam folder.
Typically, this process takes two to three weeks, but you can speed it up considerably with the right email warm-up tool. Using a warm-up tool can also improve the effectiveness of your email campaigns and help you avoid getting flagged as spam.
Email warm-up tools can automate this process, send emails to gradually larger groups of recipients, and monitor the progress.
Once you've finished the fundamental warm-up with an email warm-up tool, you should proceed cautiously when sending cold emails, email marketing, and newsletters.