SonicWall error message - 554 No SMTPd here
554 No SMTPd here
Emails are blocked by SonicWall with this error message.
The error means SonicWall considers one of Mail-List.com's IP addresses to have a flagged reputation. (potentially problematic IP).
How to Fix
In SonicWall, reputations are considered at the connection level. Add all Mail-List.com's IP Addresses as Trusted Connections.
For a complete list of Mail-List.com's IP Addresses, please click here.