Deletion of mail from Junk mailbox

[Doug Hardie]

I have a pigeon sive running which directs some of my received mail to the Junk folder.  That works just fine.  However, a couple minutes later, it is moved to Deleted mailbox and deleted from Junk.  At first I thought my client was doing that so I shut down the client and it still happens.  Here are the log entries:

Jul  2 00:36:31 mail dovecot: imap(doug): copy from INBOX: box=Junk, uid=10842, msgid=<F3C67E609C1A1BC4DB924CEA5FE12C76 at ze>, size=3340, from="jnilj" <hr at bjwmt.com>
Jul  2 00:36:31 mail dovecot: imap(doug): delete: box=INBOX, uid=55719, msgid=<F3C67E609C1A1BC4DB924CEA5FE12C76 at ze>, size=3340, from="jnilj" <hr at bjwmt.com>
Jul  2 00:39:33 mail dovecot: imap(doug): copy from Junk: box=Deleted Messages, uid=31049, msgid=<F3C67E609C1A1BC4DB924CEA5FE12C76 at ze>, size=3340, from="jnilj" <hr at bjwmt.com>
Jul  2 00:39:33 mail dovecot: imap(doug): delete: box=Junk, uid=10842, msgid=<F3C67E609C1A1BC4DB924CEA5FE12C76 at ze>, size=3340, from="jnilj" <hr at bjwmt.com>
Jul  2 00:50:29 mail dovecot: imap(doug): expunge: box=Junk, uid=10842, msgid=<F3C67E609C1A1BC4DB924CEA5FE12C76 at ze>, size=3340, from="jnilj" <hr at bjwmt.com>
Jul  2 00:50:29 mail dovecot: imap(doug): expunge: box=INBOX, uid=55719, msgid=<F3C67E609C1A1BC4DB924CEA5FE12C76 at ze>, size=3340, from="jnilj" <hr at bjwmt.com>

Is this the intended way the Junk maibox is supposed to work?  I couldn't find any settings that appear to control (or affect) this behavior.  

— Doug