We are facing the exact same error on every new installation the last days. We use KVM virtualization, and install Virtualmin on Centos 7.
When setting up a virtual server and trying to connect to a user the following error shows up and connection is not possible.
saslauthd: DEBUG: auth_pam: pam_authenticate failed: User not known to the underlying authentication module
saslauthd: do_auth : auth failure: [user=mboziki] [service=smtp] [realm=issuefashion.gr] [mech=pam] [reason=PAM auth error]
saslauthd: pam_unix(smtp:auth): check pass; user unknown
saslauthd: pam_unix(smtp:auth): authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
I am aware that putting an -r argument on FLAGS on file /etc/sysconfig/saslauthd fixes the problem but I would like to know if there is an solution to prevent this from happening(whether I am doing something wrong).