An open relay is an improperly configured Simple Transfer Mail Protocol (SMTP) server allowing the unauthorized relay of email. Spammers can connect to the server and use it to send email while forging the sender information of the messages.
Some blocklists actively target open relays to block the abusive practices of spammers who use these unsecured servers. To avoid the issue, it is common practice to disable the relay function altogether.
How to check for open relays
By default, relays are sometimes set to open.
Use the following service to check if you have an open relay:
How to close or avoid open relays
Typically your email servers are controlled by your email administrator, IT department, or Email Service Provider (ESP). To close an open relay, you need to:
- Contact the group that controls your email servers.
- Ask them to configure your email server so that the mail relay parameter only sends email from authorized IPs and domains.
- Ensure proper security protocols are in place for your server.