RoundCube SMTP error (454)

[calport]

What does the log file say?

Also see

Smtp error (454) authentication failed

Well, @mantas8 and I worked on this and the issue is now resolved. I had to do the following to resolve the issue: create a subdomain, vps.domain.tld, for hostname of server Virtualmin was running on change the hostname from the default that Contabo sets to vps.domain.tld create subdomains for name servers Rerun Post-Install Wizard and apply name servers Request SSL certificate for vps.domain.tld and apply to webmin / usermin / postfix / dovecot et al. Install Roundcube Troubleshoot SASL (as …