I have the same smtp information registered for all development, staging, and production, but I get errors sending emails outside of the development environment.
I would appreciate it if someone could tell me what the cause is.
The error above is an authentication error happening on the Email Provider’s end and is likely caused because the SMTP provider rejects the request due to the fact that the submitted credentials do not have the necessary permissions.
You can check out this knowledge article that provides the steps needed to resolve this issue.
The error message described above is pointing out exactly where the issue resides, being an authentication error on the custom SMTP provider’s end. The reason why this might still be working in the development environment is for testing purposes, presuming that the IP address is implicitly trusted by Lark’s SMTP server or within a permitted range.
But when your staging/production servers try to connect, their IPs are not recognized, leading to authentication failures, so the reason why this is not allowed on other environments is because of firewall restrictions, so the associated IP addresses would have to be whitelisted on the provider’s end. This is also mentioned in our Auth0 IP Addresses for Allow Lists documentation
if you’ve configured an on-premise SMTP provider in Auth0, then you may need to configure your firewall to allow inbound traffic from Auth0.