The Open Relay is a Simple Mail Transfer protocol that allows anyone to send emails to anyone from your server.
Through the Open Relay, anyone can send emails to anyone without authentication of domain and sender information from your server.
To avoid Open Relay from your server or smartermail, you need to :
1. You can configure your email server with an authorized server IP address and domain name only to send emails.
For this, you need to Enable SMTP authentication from SmarterMail.
1. log in to Smartermail using the system administrator.
2. Click on the Domains icon and edit the desired domain.
3. Click on the Configuration tab.
-On the Security card, enable Require SMTP Authentication.
4. Click Save.
2. You need to set the proper security protocol in your Mailserver.
- To ensure the protocol setting,
1. log in to SmarterMail as a System Administrator
2. Click on the Settings icon.
3. Click on Protocols in the navigation pane.
4. Go to SMTP IN
5. In SMTP IN, find the Allow Relay,
- Set it to Nobody to stop the Open relay. - It is strongly recommended to stop the Open relay.
- However, you can set the type of relays as follows:
- Nobody - Restricts sent mail to only work via SMTP authentication and with accounts on the local SmarterMail Server.
- Only Local Users - Limits relay access to users for a valid domain on your SmarterMail Server.
- Only Local Domains - Limits relay access only to mail hosts on your SmarterMail Server.
3. You can disable inbound traffic to SMTP port (25) and set SMTP service on other ports like 587.
- If you disable inbound traffic to the SMTP default port (25), it will not allow internet users to access the SMTP server.
