Do not accept emails from ANY (Avoid open relay) - applicable to MTA mode only
Critical
Explanation
Adding Any
will result in an open relay, allowing anyone on the internet to send emails through Sophos Firewall.
Resolution
- Go to PROTECT > Email > General settings.
- Ensure that SMTP deployment mode is set to
Mail Transfer Agent (MTA)
.
Note
You are at the MTA mode if you are seeing the Switch to legacy mode button. The legacy mode is not compatible with Sandstorm for Email.
- Go to PROTECT > Email > ... > Relay settings.
- Ensure that
Any
is not added under Host based relay > Allow relay from hosts/networks. - Click Apply.