You can try recreate email if it wasn't used yet or try change password for it.
check is there file: /etc/virtual/domainname.com/passwd
yes of course i'm using real domain name. the result same like picture i'm send before. no luck in here, kind regardsI hope you using your real domain name instead of domainname.com?
In such case you can recreate this dir with passwd-file:
rm -rf /etc/virtual/domainname.com
mkdir /etc/virtual/domainname.com
:> /etc/virtual/domainname.com/passwd
chown -R mail:mail /etc/virtual/domainname.com
or if dir exists - only last two commands to create this file