Emails can be filtered or blocked for several reasons:
Spammy Content: Emails with suspicious or overly promotional content often get flagged. Poor Sender Reputation: ESPs track the reputation of senders; a poor reputation can lead to emails getting blocked. Unverified Domains: Emails from unverified or unknown domains are more likely to be blocked. High Bounce Rates: A high rate of bounced emails can trigger filters and blocks.