There are several reasons why email marketers might choose to use port 2525:
ISP Blocking: Some ISPs block port 25 to reduce spam, making it necessary to use an alternative port like 2525. Firewall Restrictions: Certain firewalls may restrict traditional SMTP ports, and port 2525 can provide a way around these limitations. Reliability: Using an alternative port can improve the reliability of email delivery, ensuring that marketing messages reach their intended recipients.