KBExit I've never used the queue worker inside a CRON job, but since it works for the database queue there's no reason it wouldn't work with the redis queue. I guess the main difference is that it will create a lot more connects and disconnects to the redis server compared to a continuously running worker.
So there is no email server issue after all?
The error you shared above indicated you used the SMTP driver with wrong credentials. Please clarify whether you are using Mailgun via SMTP or via API.
