Creating Dovecot Master user throws "Username character disallowed by auth_username_chars : 0x2a " error

[David Okwii]

Hello,

Am trying to create a master user on dovecot. However, it throws dovecot:
auth: plain(?,127.0.0.1): Username character disallowed by
auth_username_chars: 0x2a (username: loginuser*master) ".

#telnet localhost 143

Trying 127.0.0.1...


Connected to localhost.


Escape character is '^]'.


* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE
STARTTLS AUTH=PLAIN
1 login loginuser*master mypassword


1 NO [AUTHENTICATIONFAILED] Authentication failed.

# log output
dovecot: auth: plain(?,127.0.0.1): Username character disallowed by
auth_username_chars: 0x64 (username: master)

# cat passwd.master

master:{SHA}LORtG60Uqg2bPSlOB8PW2cLI0TE=

#And here's the output of my dovecot -n

# 2.0.16: /usr/local/etc/dovecot/dovecot.conf
# OS: FreeBSD 8.2-RELEASE amd64
auth_master_user_separator = *
disable_plaintext_auth = no
mail_location = maildir:~/Maildir
namespace {
  inbox = yes
  location =
  prefix = INBOX.
  separator = .
  type = private
}

passdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf
  driver = sql
}
passdb {
  args = /usr/local/etc/dovecot/passwd.master
  driver = passwd-file
  master = yes
}
protocols = imap pop3
service auth {
  client_limit = 6000
}
service imap {
  process_limit = 2048
  vsz_limit = 1256 M
}
service pop3 {
  process_limit = 2048
}

userdb {
  args = /usr/local/etc/dovecot/dovecot-sql.conf
  driver = sql
}
protocol pop3 {
  pop3_uidl_format = UID%u-%v
}

I don't know what am doing wrong. Any help would be welcome. Thanks
-- 
Thanks & regards,
David Okwii,
Mobile(default): +256-791-040-262

Christ in me the Hope of Glory(Col.1:27)