|
|
You are here: Home>> Tutorial>>Open Relay
- What is an open relay?
An open relay, also known as third-party relay, is an e-mail server that
allows anyone on the Internet to connect to it and send e-mail.
For example, "Joe User", dialed in through "Big ISP" can connect
to the open relay and send his mail to any destination he chooses.
This abuse is popular with spammers.
- Checking for open relay
How do I test my server for an open relay.
The way to test your server is to telnet to
the IP address in question on port 25 from a different Internet Service
Provider and manually initiate an SMTP transaction. If you can send mail
from yourself from the different ISP to an outside e-mail address, your server is an open
relay.
- Why should I close my open relay?
Your server may encounter severe problems if it is
used to send unsolicited bulk e-mail (spam). These problems may include the
server crashing or being blocked from sending e-mail to some domains.
| |
