As you know SMTP (Simple Mail Transfer Protocol) is a standard communication protocol used for transmitting electronic mail over the Internet. It is a part of the TCP/IP protocol and works on moving emails across the network. SMTP is used by email servers and clients to send and receive emails. However, many hosting providers are blocking the default port used for SMTP communication on their VPS plans for several reasons.
Port 25 is often used by spammers to send unsolicited emails. By blocking this port, hosting providers can prevent spammers from using their VPS plans to send spam emails. This helps to protect the reputation of the hosting provider and their customers. Additionally, hosting providers may block this port to prevent their VPS plans from being used for phishing attacks, DDoS attacks, and to ensure that their email service functions smoothly. Finally, hosting providers may block this port to comply with anti-spam regulations.
Phishing attacks are a type of cyber attack where attackers try to trick users into giving away sensitive information such as usernames, passwords, and credit card details. By blocking this port, hosting providers can prevent phishing emails from being sent from their VPS plans. This helps to protect the privacy and security of their customers.
DDoS (Distributed Denial of Service) attacks are a type of cyber attack where attackers flood a server with traffic to make it unavailable to users. By blocking this port, hosting providers can prevent their VPS plans from being used as part of a DDoS attack. This helps to ensure that their customers’ websites and applications remain available to users.
Also by limiting the number of emails sent per minute, hosting providers can prevent abuse of their email service, such as sending bulk or unsolicited emails, which can harm their clients and their reputation.
With all the above being said above, Hosting providers may block this port also to comply with anti-spam regulations. Many countries have laws and regulations in place to prevent spam emails. By blocking this port, hosting providers can ensure that they are complying with these regulations.