User found but password failure

[Mauricio Tavares]

      Trying to figure out which step is  causing me not to be able to
login. I am using a password file,

passdb {
  driver = passwd-file
  args = scheme=SHA512-CRYPT username_format=%u /etc/dovecot/passwd
}

We will assume that the pw I created using 'doveadm pw -s
SHA512-CRYPT' matches the password I will be using to login below. I
crank the debugging mode,

auth_debug_passwords = yes
auth_debug = yes

And then try to login

[root at mail ~]# nc -t localhost 143
* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE
IDLE STARTTLS AUTH=PLAIN AUTH=LOGIN AUTH=GSSAPI] Howdy
a login raub at example.com password
[blank]

which from what I gathered from /var/log/dovecot means it found
matching username but did not match password:

secured session=lyJttvyQ9I0AAAAAAAAAAAAAAAAAAAAB        lip=::1
rip=::1 lport=143       rport=36340     resp=base64-reply (previous
base64 data may contain sensitive data)
Aug 26 03:25:52 auth: Debug:
passwd-file(raub at example.com,::1,<lyJttvyQ9I0AAAAAAAAAAAAAAAAAAAAB>):
lookup: user=raub at example.com file=/etc/dovecot/passwd
Aug 26 03:25:52 auth: Debug: client passdb out: OK      1
user=raub at example.com
Aug 26 03:25:52 auth: Debug: master in: REQUEST 1520959489      26560
 1      63ee7f45236f85fd39573a5c8a2eb46a session_pid=26563
request_auth_token
Aug 26 03:25:52 auth-worker(26562): Debug:
passwd(raub at example.com,::1,<lyJttvyQ9I0AAAAAAAAAAAAAAAAAAAAB>):
lookup
Aug 26 03:25:52 auth-worker(26562): Info:
passwd(raub at example.com,::1,<lyJttvyQ9I0AAAAAAAAAAAAAAAAAAAAB>):
unknown user
Aug 26 03:25:52 auth: Debug:
passwd-file(raub at example.com,::1,<lyJttvyQ9I0AAAAAAAAAAAAAAAAAAAAB>):
lookup: user=raub at example.com file=/etc/dovecot/passwd
Aug 26 03:25:52 auth: Error:
plain(raub at example.com,::1,<lyJttvyQ9I0AAAAAAAAAAAAAAAAAAAAB>): user
not found from any userdbs
Aug 26 03:25:52 auth: Debug: master userdb out: NOTFOUND        1520959489
Aug 26 03:25:52 imap: Error: Authenticated user not found from userdb,
auth lookup id=1520959489 (auth connected 1 msecs ago, handshake 0
msecs ago, request took 1 msecs, client-pid=26560 client-id=1)
Aug 26 03:25:52 imap-login: Info: Internal login failure (pid=26560
id=1) (internal failure, 1 successful auths): user=<raub at example.com>,
method=PLAIN, rip=::1, lip=::1, mpid=26563, secured,
session=<lyJttvyQ9I0AAAAAAAAAAAAAAAAAAAAB>

Per [1] I decided to see what the  response (base64-reply) I am
submitting to dovecot looks like:

echo 'base64-reply' | base64 -d
raub at example.compassword

Which has the right username and password but follows the userpassword
format, not useruserpassword as I was led to believe by [1]. Is that
to be expected? If it is then the issue is further down the line.

[1] https://wiki.dovecot.org/Debugging/Authentication