Many ISPs block port 25 (and many others are starting to block other “alternate” SMTP ports) as this is the standard port for mail delivery. They block the port for a variety of reasons; the most common reasons are to prevent you from running your own mail server and to stop devices on their network that are infected with spyware or malware from sending and spreading spam. Port 25 is not available on our primary mail systems to prevent incoming spam from going around our gateways.
We offer multiple SMTP ports to aid in allow users to send mail through our mail servers.
- 23 (TLS supported / available)
- 26 (TLS supported / available)
- 465 (SSL required)
- 587 (TLS supported / available)
- 2025 (TLS supported / available)
- 2525 (TLS supported / available)
- 6025 (TLS supported / available)
- 6465 (SSL required)
- 8080 (TLS supported / available)
Why so many? Unfortunately, some ISPs are beginning to block 26 and 2525. So we’ve had to open up additional ports to make sure our customers are not restricted to using the poor quality ISP SMTP servers to deliver mail. We recommend using 465 (SSL required) first than 587 (TLS supported / available) to send mail. If these do not work, try using any of the other ports we have available.