When you start sending mailings on a new mailbox, warming up is the first important step to ensure deliverability and avoid penalties from mailing services. During the warm-up process, you need to carefully monitor the activity, starting with small volumes of emails and gradually increasing them. For control and testing, I recommend using top email warm-up
https://snov.io/email-warm-up . The platform provides functions for testing delivery, setting up DMARC and SPF records, which will help you ensure that your emails do not end up in spam. Using these methods, you will ensure a stable result and high efficiency of your email campaigns.