Hello
Short version:
Dovecot's dsync from release 2.3.7.2 (default install from focal repository) running under Ubuntu 20.04.6 LTS server is not deleting mails on the identical remote server.
Background:
I have installed this configuration using automated scripts several times for customers. Functionally identical installations done on Ubuntu LTS Servers 14.04, 16.04 and 18.04 are running for years without problem. Now I have tried several times to do the same with Ubuntu 20.04 and can't get dsync to work properly. Last year I could fall back onto Ubuntu 18.04. This time I can't and must install the latest versions.
Setup:
Two VM's on ESXI 6.7U3 with 36 GB of disk space and 8 GB ram, 10kspinning disks or SSD with HW RAID1
Mariadb for mail users (master - master synched)Postfixadmin to manage the usersPostfixDovecotSome with RoundcubeThe clients can connect to either one server and connect SMTPS(465 or 587) or POPS (995) to the servers.
The two servers connect on a dedicated network without routing(SSL, port > 49000). The synchronization network has no mail traffic except the one that synchronizes the servers.
Additionally the two servers are ntp peers within a few ms - butthat is only relevant to know when we start comparing logs from the machines
Problem description:
When I send one mail to one account, it is immediately synched tothe other server. This is also seen in the dovecot log and I can connect to any one of the two servers to download it.
When I read and delete the mail on one server, it is NOT deletedon the other server. I do not see a trigger in the dovecot log that kicks on the synchronization (like I do when sending mails). As a result, the mail can be downloaded and deleted from both servers.
When I send a new mail to one of the two servers, thesynchronization takes place and the mail that I read and deleted is also gone on the remote (backup) server.
Changing users, rights in dsynch.conf , SSL on or off, orconnecting to PLAIN ports 25, 110 or 143 is never improved it. Iptables or ufw are not in use.
In my case I have systems using the server that' don't likeduplicate mails and the servers fail the acceptance test criteria.
This causes duplicate mail if one client is connecting to theother server. Since a new mail fixes that duplicate mail problem, it is likely that up to now nobody detects it and complains about this. Especially if the servers would run in a primary - backup mode. I assume that's why I could not find reportings on the web until now.
Dovecot -n:
See attachments
Log from my automated test system using Ubuntu 20.01 and focal default dovecot package from repository (dovecot 2.3.7.2):
2021-11-22 18:20:06.30 -
2021-11-22 18:20:06.81 - SMTP Server: mail-pri Port 465 TLS - User: user@test.ch - To: user@test.ch - Subject: Test 2021-11-22 18:20:06, Msg 00001
2021-11-22 18:20:14.90 -
2021-11-22 18:20:15.37 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:06, Msg 00001 (retr no delete)
2021-11-22 18:20:17.32 -
2021-11-22 18:20:17.77 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:06, Msg 00001 (retr no delete) -> synchronization worked when sending mails
2021-11-22 18:20:27.52 -
2021-11-22 18:20:27.96 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:06, Msg 00001 (retr and delete)
2021-11-22 18:20:30.72 -
2021-11-22 18:20:31.17 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:06, Msg 00001 (retr and delete) -> synchronization failed after POP3 connection with delete
2021-11-22 18:20:53.06 -
2021-11-22 18:20:53.66 - SMTP Server: mail-sec Port 465 TLS - User: user@test.ch - To: user@test.ch - Subject: Test 2021-11-22 18:20:53, Msg 00002
2021-11-22 18:20:57.91 -
2021-11-22 18:20:58.33 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:53, Msg 00002 (retr no delete)
2021-11-22 18:21:00.82 -
2021-11-22 18:21:01.27 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:53, Msg 00002 (retr no delete)
2021-11-22 18:21:04.65 -
2021-11-22 18:21:05.11 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:53, Msg 00002 (retr and delete)
2021-11-22 18:21:08.95 -
2021-11-22 18:21:09.40 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-22 18:20:53, Msg 00002 (retr and delete)
2021-11-22 18:21:39.50 -
Reference log with the same installation using Ubuntu 18.04 and bionic default package form repository (dovecot 1:2.2.33.2-1ubuntu4.7):
2021-11-23 13:55:06.93 -
2021-11-23 13:54:49.86 - SMTP Server: mail-pri Port 465 TLS - User: user@test.ch - To: user@test.ch - Subject: Test 2021-11-23 13:54:49, Msg 00001
2021-11-23 13:55:06.93 -
2021-11-23 13:55:07.47 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-23 13:54:49, Msg 00001 (retr no delete)
2021-11-23 13:55:13.10 -
2021-11-23 13:55:13.66 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-23 13:54:49, Msg 00001 (retr no delete) -> synchronization OK for sending mails
2021-11-23 13:55:22.32 -
2021-11-23 13:55:22.87 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-23 13:54:49, Msg 00001 (retr and delete)
2021-11-23 13:55:27.91 -
2021-11-23 13:55:28.35 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - no mails found -> synchronization OK for deleting mails
2021-11-23 13:55:36.48 -
2021-11-23 13:55:37.00 - SMTP Server: mail-sec Port 465 TLS - User: user@test.ch - To: user@test.ch - Subject: Test 2021-11-23 13:55:36, Msg 00002
2021-11-23 13:55:45.94 -
2021-11-23 13:55:46.48 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-23 13:55:36, Msg 00002 (retr no delete)
2021-11-23 13:55:55.59 -
2021-11-23 13:55:56.14 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-23 13:55:36, Msg 00002 (retr no delete)
2021-11-23 13:56:05.70 -
2021-11-23 13:56:06.26 - POP3 Server: mail-pri Port 995 TLS - User: user@test.ch - From: user@test.ch - Subject: Test 2021-11-23 13:55:36, Msg 00002 (retr and delete)
2021-11-23 13:56:38.70 -
2021-11-23 13:56:39.12 - POP3 Server: mail-sec Port 995 TLS - User: user@test.ch - no mails found
P.S. I compared the dovecot and postfix config files between these two versions and both servers and they are functionally identical except where they need to be different.
I would appreciate any help here. If needed I can create log files that show that nothing is triggered as well as produce wireshark captures (port 25 and 110) or the link for the synch (currently with ssl but I could change that if needed).
Thanks in advance
Otto
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