Question regarding replication - duplicate emails

[Remko Lodder]

Hi Aki,

Uhm well, that’s pretty hard not to do so…
Mail.app only has one “Delete” option and that triggers the situation.
My support application fetches the email and then deletes it (basically the same as Mail.app).
My customers use a variety of MUA’s and they see the same behaviour..

I think the “notification” for the removal is not yet on the other machine, but it sees something
changing and thinks “well I have this new message, that you do not have, sync it”.

Thanks,
Remko

> On 21 Oct 2017, at 15:06, Aki Tuomi <aki.tuomi at dovecot.fi> wrote:
> 
> Maybe you could not delete the message instantly, but keep track of last seen UID. UIDs increase monotonically, so you can rest assured that next arriving email has larger UID.
> 
> Then you can bulk delete mails that are older than one day.
> 
> Aki
> 
>> On October 20, 2017 at 8:01 PM Remko Lodder <remko at FreeBSD.org> wrote:
>> 
>> 
>> Hi,
>> 
>> Anyone has suggestions? The situation also happends when I “delete” a message from my Phone.
>> It seems to get replicated instantly and the just deleted email is back in the mailbox again.
>> 
>> I did remove HA Proxy support in the meantime to rule that out and I have enabled the default
>> replication_max_conns.
>> 
>> thanks
>> Remko
>> 
>>> On 13 Oct 2017, at 11:56, Remko Lodder <remko at FreeBSD.org> wrote:
>>> 
>>> Dear Dovecot and community,
>>> 
>>> We run a small email service for our customers, based on two machines that are made “redundant or clustered” by using the replication feature of Dovecot.
>>> This works well, for most emails.
>>> 
>>> Sometimes the following happends:
>>> 
>>> Email to our support database arrives at the inbox.
>>> Every period a cronjob looks into that mailbox and parses the information and makes a support ticket from that message.
>>> The cronjob deletes the email afterwards and sees whether there are more new mails or not.
>>> 
>>> In between the deletion and the (next) check, the email gets “resynced” again from the “other machine”, and is seen as a new
>>> email by the cronjob and gets handled again. So basically we get two tickets for one email. After that second run the email is
>>> no longer replicated.
>>> 
>>> This behaviour can also be seen via webmail and email clients, this suggests that the replication might not be aware (enough) that
>>> the replication is occurring or that an item already had been synced from A to B (and does not need to get back from B to A after A
>>> deleted it).
>>> 
>>> Is there a way to fiddle with the acknowledgement timing or give the processes some more space/time to get on par with eachother?
>>> 
>>> Below is the configuration of machine B, they are synchronised through puppet, so only the hostname and IP addresses are different.
>>> (so for replication, A has: tcps:hostname_of_b:12346 and B has tcps:hostname_of_a:12346). Also note that HAproxy is prepared but
>>> not in use at all.
>>> 
>>> # 2.2.33.1 (e9afa7f18): /usr/local/etc/dovecot/dovecot.conf
>>> # Pigeonhole version 0.4.20 (7cd71ba)
>>> # OS: FreeBSD 11.1-RELEASE amd64
>>> auth_mechanisms = plain login
>>> disable_plaintext_auth = no
>>> doveadm_password =  # hidden, use -P to show it
>>> haproxy_trusted_networks = IPv4_Haproxy IPv6_Haproxy
>>> lda_mailbox_autocreate = yes
>>> lda_mailbox_autosubscribe = yes
>>> lmtp_save_to_detail_mailbox = yes
>>> mail_fsync = always
>>> mail_location = sdbox:~/sdbox
>>> mail_plugins = " quota notify replication"
>>> managesieve_notify_capability = mailto
>>> managesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date index ihave duplicate mime foreverypart extracttext imapsieve vnd.dovecot.imapsieve
>>> namespace {
>>> inbox = yes
>>> location =
>>> mailbox Drafts {
>>>   auto = subscribe
>>>   special_use = \Drafts
>>> }
>>> mailbox Junk {
>>>   special_use = \Junk
>>> }
>>> mailbox Sent {
>>>   auto = subscribe
>>>   special_use = \Sent
>>> }
>>> mailbox "Sent Messages" {
>>>   special_use = \Sent
>>> }
>>> mailbox Spam {
>>>   auto = subscribe
>>>   special_use = \Junk
>>> }
>>> mailbox Trash {
>>>   auto = subscribe
>>>   special_use = \Trash
>>> }
>>> prefix =
>>> separator = .
>>> }
>>> passdb {
>>> driver = pam
>>> }
>>> plugin {
>>> imapsieve_mailbox1_before = file:/usr/local/lib/dovecot/sieve/report-spam.sieve
>>> imapsieve_mailbox1_causes = COPY
>>> imapsieve_mailbox1_name = Spam
>>> imapsieve_mailbox2_before = file:/usr/local/lib/dovecot/sieve/report-ham.sieve
>>> imapsieve_mailbox2_causes = COPY
>>> imapsieve_mailbox2_from = Spam
>>> imapsieve_mailbox2_name = *
>>> mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
>>> mail_log_fields = uid box msgid size
>>> mail_replica = tcps:hostname_of_machine_a:12346
>>> sieve = ~/.dovecot.sieve
>>> sieve_after = /usr/local/etc/dovecot/sieve/after/
>>> sieve_before = /usr/local/etc/dovecot/sieve/global/
>>> sieve_pipe_bin_dir = /usr/local/lib/dovecot/sieve
>>> sieve_plugins = sieve_imapsieve sieve_extprograms
>>> sieve_vacation_dont_check_recipient = yes
>>> }
>>> postmaster_address = postmaster at ourdomain.tld
>>> protocols = imap pop3 lmtp sieve
>>> replication_max_conns = 100
>>> service aggregator {
>>> fifo_listener replication-notify-fifo {
>>>   mode = 0666
>>> }
>>> unix_listener replication-notify {
>>>   mode = 0666
>>> }
>>> }
>>> service auth {
>>> unix_listener /var/spool/postfix/private/auth {
>>>   mode = 0666
>>> }
>>> }
>>> service doveadm {
>>> inet_listener {
>>>   port = 12346
>>>   ssl = yes
>>> }
>>> }
>>> service imap-login {
>>> inet_listener imap_haproxy {
>>>   haproxy = yes
>>>   port = 10143
>>> }
>>> inet_listener imaps_haproxy {
>>>   haproxy = yes
>>>   port = 10144
>>>   ssl = yes
>>> }
>>> service_count = 1
>>> }
>>> service imap {
>>> process_limit = 1024
>>> }
>>> service lmtp {
>>> inet_listener lmtp {
>>>   address = IPv4, IPv6, 127.0.0.1 ::1
>>>   port = 24
>>> }
>>> unix_listener /var/spool/postfix/private/dovecot-lmtp {
>>>   group = postfix
>>>   mode = 0600
>>>   user = postfix
>>> }
>>> }
>>> service pop3 {
>>> process_limit = 1024
>>> }
>>> service replicator {
>>> process_min_avail = 1
>>> unix_listener replicator-doveadm {
>>>   mode = 0666
>>> }
>>> }
>>> ssl_ca = </usr/local/etc/letsencrypt/live/host.ourdomain.tld/fullchain.pem
>>> ssl_cert = </usr/local/etc/letsencrypt/live/host.ourdomain.tld/cert.pem
>>> ssl_client_ca_file = /usr/local/certificates/letsencrypt-ca.pem
>>> ssl_key =  # hidden, use -P to show it
>>> ssl_protocols = !SSLv2 !SSLv3
>>> userdb {
>>> driver = passwd
>>> }
>>> verbose_proctitle = yes
>>> protocol lmtp {
>>> auth_username_format = %n
>>> mail_plugins = quota sieve replication notify
>>> postmaster_address = postmaster at ourdomain.tld
>>> }
>>> protocol lda {
>>> mail_plugins = " quota notify replication sieve replication notify"
>>> }
>>> protocol imap {
>>> imap_client_workarounds = delay-newmail
>>> mail_max_userip_connections = 50
>>> mail_plugins = " quota notify replication imap_quota imap_sieve"
>>> }
>>> 
>> 

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