Reappearing emails

[Ron Cleven]

We have been running Dovecot 2.2.10 with a pair of CentOS 7 boxes with 
replications for the past year.  We have been quite happy with the 
performance and reliability.  Recently we received a report from an 
Android IMAP user that emails that he deleted without reading would 
often reappear in his INBOX.  At first I thought it might be some quirky 
incompatibility with his email client, but I found that I could easily 
reproduce it in Roundcube by dragging an unread email to Trash.  I have 
been monitoring this forum fairly religiously and don't recall seeing 
any similar reports.  I plan to capture the IMAP wire interactions, but 
before doing that, I thought I would submit this to the IMAP gods to see 
if anyone had heard of this and/or if there is some newer version that 
might resolve the problem.

This particular customer contacted his email vendor and asked them to 
analyze the problem.  The actual log data is gigantic, so I just pasted 
in the vendor's narrative below in case it helps.  Otherwise, as I said, 
I will capture a similar interaction at the wire level and follow up here.

Vendor's narrative:

You had 8 messages in the Inbox, and moved two to Trash.
The server notified the app on the push connection (for Inbox) that 
there are now 6 messages.
By the time the app got around to catch up with that (it did the Trash 
folder first), the server said "oh wait, there are 8 messages, not 6" 
(in the Inbox), and so the app synced them in, just as reported.

app selecting the Inbox, server saying there are 8 messages there
app moving UID 729 and 730 to Trash
(push) server saying Trash now has 34 messages
(push) server saying two messages gone from Inbox, 6 left
(push) 6 messages left in Inbox becoming 8
(push) and here they are (the two new ones)

Thanks,
Ron