Forum Discussion
Exchange Server default relays
Hello
Got a question about exchange sever behavior
When I telnet to my onpremise exchange server via tcp/25 I can send an email to anyone within accpeted domian from any e-mail. Even if email address exact like this: mailto:domain@domain.domain
I have no relay configuredt. It is fresh installed Exchnage
why this happens and how to prevent this?
2 Replies
- Exchange Server is designed by default to accept SMTP connections from all sending mail servers, however it rejects messages where the recipient is not an accepted domain your Exchange organisation (it would constitute an open relay if it did accept and relay these messages).
vusald https://www.techrepublic.com/article/prevent-open-relays-on-exchange-server/#:~:text=open%20relays%2C%20follow%20these%20steps%3A%201%20Go%20to,connect%20to.%20%28TCP%2FIP%20port%2025%20is%20for%20SMTP.%29
