lda / postfix / dovecot -- bounced messages not working

[Scott Ruckh]

I saw another thread about this topic, but I did not understand the 
solution. . .

I recently discovered my bounced messages were not getting delivered.  
Obviously since I was not getting any messages, I thought everything was 
fine.

Anyway, my maillog has entries similar to below for bounced messages:

Mar 29 10:48:09 firewall postfix/pipe[9089]: 19565807: 
to=<myuser at my.domain>, relay=dovecot, delay=0.11, 
delays=0.02/0.01/0/0.08, dsn=5.3.0, status=bounced (command line usage 
error. Command output: lda: Fatal: Invalid -f parameter: Missing domain 
)

In the previous thread discussing this issue it mentioned that this was 
a dovecot error and possibly due to a dovecot 2.3.0 upgrade.  I am 
running dovecot-2.3.0-1.1 on a CentOS 7 server.  The solution from the 
other thread simply stated that the original poster is instead using 
lmtp instead of lda, or at least that it was I got from the thread.

If using lmtp instead of lda is the correct solution, could I get an 
example of what configuration changes need to be made to make that 
happen?

Otherwise, has anyone else seen this error and know the solution to make 
it work.

My current dovecot configuration for postfix (master.cf) is using the 
de-facto standard from many web docs:

dovecot   unix  -       n       n       -       -       pipe
    flags=DRhu user=vmail:vmail argv=/usr/libexec/dovecot/deliver -f 
${sender} -d ${recipient}

This is the same configuration that was originally setup and has worked 
for years; until the bounced message problem was recently discovered.

If anyone has seen this error and knows the solution, I would appreciate 
the help.

Thank You.
Scott