ISPs use a variety of factors to calculate sender reputation. These include:
Spam Complaints: The number of recipients who mark your email as spam. Bounce Rates: The percentage of emails that are returned as undeliverable. Engagement Rates: The level of interaction recipients have with your emails, such as opens and clicks. Sending Frequency: How often you send emails to your list. Blacklistings: Whether your sending IP or domain is listed on any email blacklists.