Some of the common firewall settings that you should review include:
Port Settings: Ensure that the ports commonly used for email traffic (e.g., port 25 for SMTP) are open. IP Whitelisting: Add trusted email servers to the whitelist to prevent them from being blocked. Content Filtering: Check the criteria for blocking emails based on content. Make sure your marketing content doesn’t trigger these filters. Rate Limiting: Ensure rate limits are set to allow a reasonable amount of email traffic without triggering security measures.