The release of Qobrix v39.1.2 slightly improves SMTP error handling.
SMTP Error Handling
In this version we have added additional checks to improve error handling. One of the common scenarios that we’ve seen recently is a failure to send email due to the outgoing mail server (SMTP) not being available. This is particularly important in the Forex onboarding process, for example. So now instead of user visible errors, we’ll continue with the process and log such failures to the System Logs.