POP3 server fails to replicate deletions

[Stephen Gildea]

When I delete messages with POP3, the change doesn't get replicated.

To reproduce:
run the pop3 server from the command line, type this to it:

DELE 1
QUIT

This correctly deletes the first message on the local server, but it
does not send a replication notify message.

Poking around a bit with gdb, it appears that the pop3 server decides
incorrectly that the changes it is making are not worth notifying
about.  It is hard to find something that doesn't happen, and I would
appreciate suggestions for further debugging this case.

I do get the expected replication when new mail arrives and also when
I manipulate my mailbox with IMAP.

I have tested this with Dovecot 2.3.7.2 (on Ubuntu 20.04) and with the
git HEAD, 2.3.14+.  What may be the same bug was reported on this list
last August against Dovecot 2.3.8, but it got no reply then.

My mail store is on a local ext4 file system.
I have replication enabled in my configuration:

$ doveconf mail_plugins
mail_plugins =  mail_crypt notify replication
$ doveconf -f protocol=pop3 mail_plugins
mail_plugins =  mail_crypt notify replication