- dovecot - dovecot.org

sudden performance drop - i/o related
by Marcin Gryszkalis 11 May '21

11 May '21

Hi I have exim/dovecot server that worked great for last few years and two weeks ago it got ill ;) First were users reporting errors on saving mails to Sent (timeouts). Now the logs are infested with warnings about long waits: May 10 10:18: Maildir /mail/xxx Synchronization took 193 seconds (1 new msgs, 0 flag change attempts, 0 expunge attempts) May 10 10:18: Maildir /mail/xxx Synchronization took 125 seconds (1 new msgs, 0 flag change attempts, 0 expunge attempts) May 10 10:18: Maildir /mail/xxx Synchronization took 211 seconds (1 new msgs, 0 flag change attempts, 0 expunge attempts) May 10 10:18: Maildir /mail/xxx Synchronization took 107 seconds (8 new msgs, 0 flag change attempts, 0 expunge attempts) May 10 10:18: Transaction log file /mail/xxx was locked for 36 seconds (Mailbox was synchronized) May 10 10:18: Transaction log file /mail/xxx was locked for 160 seconds (Mailbox was synchronized) May 10 10:18: Transaction log file /mail/xxx was locked for 72 seconds (Mailbox was synchronized) May 10 10:18: Locking transaction log file /mail/xxx took 60 seconds (syncing) May 10 10:18: Locking transaction log file /mail/xxx took 38 seconds (syncing) May 10 10:18: Locking transaction log file /mail/xxx took 35 seconds (syncing) It looks like i/o risen from 150writes/s to 500writes/s (in top hours) - but there's no real change in number of emails or the volume. Number of users is steady (~100 active users, ~250 imap sessions), number of emails (by count or by volume) is rising and falling within 15% margin. The box is FreeBSD 11.4, dovecot is 2.3.13. Filesystem is ZFS, disks are fine, free space is around 20% (~200GB) Layout is Maildir. CPU is not overloaded (2x6core), same with memory (48GB). I didn't change anything in configuration. Tonight I did some finetuning like maildir_copy_with_hardlinks=yes or mail_fsync=never/optimized (I'm not happy with that but I'm afraid it won't really help and I'll be able to revert that). I'm also thinking about switching from Maildir to sdbox (I know it won't hurt). I don't know where to look to find where the i/o goes. I don't have any metrics/stats enabled (I looked at the docs but it looks it's not really simple and needs some digging to get valuable config). Maybe somebody has suggestions what to look for? For detailed per-process stats I need to rebuild kernel with dtrace (other night I guess)... Simple top (in i/o mode - similar to linux's iotop) doesn't catch short living processes (like LDA deliveries). best regards -- Marcin Gryszkalis, PGP 0xA5DBEEC7 http://fork.pl/gpg.txt

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mdbox / selecting folder accesses hundrets of others
by Florian Lohoff 10 May '21

10 May '21

Dovecot: 2.3.4 Hi, i am debugging a problem where after a force-resync removed all cache files (All files are 44 byte). Trying to open a folder takes literally minutes (Huge mailbox - 220K folder, 45GByte compressed storage) After i straced the imap process i can see the imap process accesses hundrets of other completely unrelated folders: Thats from the logfile - You can see mutt selecting the mailbox "zzzzzzt": May 07 18:05:19 imap(inbox@wasteland)<20381><hlkrmL/B5qwgAwDvnxMdAGcc/5MSpYxQ>: Debug: fts: No fts setting - plugin disabled May 07 18:05:19 imap(inbox@wasteland)<20381><hlkrmL/B5qwgAwDvnxMdAGcc/5MSpYxQ>: Debug: quota: quota_over_flag check: quota_over_script unset - skipping May 07 18:05:19 imap(inbox@wasteland)<20381><hlkrmL/B5qwgAwDvnxMdAGcc/5MSpYxQ>: Debug: Mailbox zzzzzzt: Mailbox opened because: SELECT From strace -p 20381 - This goes on for minutes opening thousands of unrelated folders. It is noteworthy that it mostly opens nested folders which are rare here: [...] open("/var/vmail/wasteland/inbox/mdbox/mailboxes/gerries/are/hawt", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 15 fstat(15, {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 getdents(15, /* 3 entries */, 32768) = 72 stat("/var/vmail/wasteland/inbox/mdbox/mailboxes/gerries/are/hawt/yeah", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 stat("/var/vmail/wasteland/inbox/mdbox/mailboxes/gerries/are/hawt/yeah/dbox-Mails", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 getdents(15, /* 0 entries */, 32768) = 0 close(15) = 0 open("/var/vmail/wasteland/inbox/mdbox/mailboxes/karl588594", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 15 fstat(15, {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 getdents(15, /* 3 entries */, 32768) = 80 stat("/var/vmail/wasteland/inbox/mdbox/mailboxes/karl588594/b3914", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 stat("/var/vmail/wasteland/inbox/mdbox/mailboxes/karl588594/b3914/dbox-Mails", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 getdents(15, /* 0 entries */, 32768) = 0 close(15) = 0 open("/var/vmail/wasteland/inbox/mdbox/mailboxes/ben", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 15 fstat(15, {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 getdents(15, /* 4 entries */, 32768) = 104 stat("/var/vmail/wasteland/inbox/mdbox/mailboxes/ben/gang", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 stat("/var/vmail/wasteland/inbox/mdbox/mailboxes/ben/gang/dbox-Mails", {st_mode=S_IFDIR|0700, st_size=4096, ...}) = 0 Reopening the same folder again is quick and seamless. So it seems this is some cache recreation code looking into other folders. I am bit puzzled on why it does this. mail_debug=yes did now show anything. Any more debug options for mdbox i might set to find out about its decisions? Flo -- Florian Lohoff f(a)zz.de Any sufficiently advanced technology is indistinguishable from magic.

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Writing an custom imap command
by Ryan Beethe 10 May '21

10 May '21

I'm interested in writing a custom imap command that behaves a bit like IDLE but synchronizes some state that is specific to my mail client / mail server. I found that stateless commands were trivial to understand, and I really like the plugin pattern for registering custom commands. But I have a few questions on how to write a long-running command that I was not able to answer by reading through the code. This mailing list seems like the best place to ask them. For reference, the source code for my custom command is here: https://github.com/Splintermail/splintermail-client/blob/dev/server/xkeysyn… Thanks, Ryan ------ 1. Why does cmd-idle.c sometimes call client_command_free()? But sometimes it doesn't? For example, cmd_idle_continue() frees it in some branches but not others. That makes no sense to me; it seems like it should be based on your entrypoint (mailbox notify callback vs input callback vs timeout callback), not based on which branch of logic within that entrypoint. 2. Why does cmd-idle.c ever call client_destroy()? That seems like something that should be invoked only by the imap process, not by any command. It calls it in cmd-idle.c:idle_callback (which is a mailbox notify callback). It invokes it after idle_sync_now() when it detects that client->disconnected is set. Maybe that happens in imap_sync_init() or something? 3. Why does cmd-idle.c ever call client_disconnect()? That also seems like the responsibility of the imap process, and not any command. idle_client_input_more() detects when i_stream_read returns -1, meaning that the client has *already disconnected*. Then it calls client_disconnect(). I think this is the crazy part... the istream is effectively unique to the imap process, so it seems unreasonable that any command is responsible for cleaning it up; it should just always happen at the imap process level before exiting, right? 4. What does client_continue_pending_input() actually do, and under what conditions does it need to be called? There is one place that you *can't* call it; there is a section in imap-client.c:client_handle_input() that calls imap-client.c:client_handle_next_command(), which calls the cmd->func(). That makes sense; that's the input trigger for the command plugin, so maybe you only have to trigger it when you are receiving input that doesn't fit into the normal command args behavior. It has a comment that says "this function is called at the end of I/O callbacks (and only there)". It _is_ called by client_input() and by client_output(), but also by: - cmd-idle.c:idle_client_input (io_add_istream callback) - cmd-append.c:client_input_append (io_add_istream callback) - imap-search.c:cmd_search_more_callback (timeout_add callback) The first two cases seem to be the only io_add_istream() commands that even exist, so that explains them. I can't explain the imap-search.c case at all. Reading through it I have really no idea what client_continue_pending_input is really doing. My command has a DONE mechanic just like IDLE so I'm pretty sure I need to invoke this function, I'm just concerned I'm going to do it wrong if I don't understand the mechanics of it.

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huge mdbox broken / Log synchronization error
by Florian Lohoff 10 May '21

10 May '21

Hi, its the second time in 6 Month i have issues with a huge mdbox. It broken in November and i restored from backup because force-resync twice didnt fix it. (And restore from borg-backup was MUCH faster than force-resync) This time i have heavy delivery into that mailbox (postfix concurrency 1) and i tried merging folders with doveadm move. The move froze and now i seem to have a broken mdbox: Errors are: May 05 10:21:09 lda(inbox(a)wasteland.rfc822.org): Error: Log synchronization error at seq=2736,offset=135540 for /var/vmail/wasteland.rfc822.org/inbox/mdbox/storage/dovecot.map.index: Extension record inc drops number below zero (uid=7757856, diff=-1, orig=0) trying root@pax:~# doveadm -D -v force-resync -u inbox(a)wasteland.rfc822.org \* now. Although this will mostly likely take 8-10 hours. Mailbox is 44GByte (Compressed mdbox) and 220K folders. This is dovecot on Debian/Stretch dovecot-core 1:2.2.27-3+deb9u7 dovecot-imapd 1:2.2.27-3+deb9u7 dovecot-ldap 1:2.2.27-3+deb9u7 dovecot-managesieved 1:2.2.27-3+deb9u7 dovecot-pop3d 1:2.2.27-3+deb9u7 dovecot-sieve 1:2.2.27-3+deb9u7 dovecot-solr 1:2.2.27-3+deb9u7 Flo -- Florian Lohoff f(a)zz.de Any sufficiently advanced technology is indistinguishable from magic.

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How to set lmtp delivery file/directory permissions?
by Kurt Fitzner 08 May '21

08 May '21

I have my postfix/dovecot virtual mail system essentially (otherwise) configured where Postfix is calling Dovecot for its virtual transport: virtual_transport = lmtp:unix:private/dovecot-lmtp But I can't for the life of me see how to change the file permissions dovecot uses to create maildir folders and files. I looked at the maildir [1], lmtp [2], and other documents and they are either silent on permissions or seem to reference a shared mail permissions document [3] that claims file and folder permissions are inherited. I want all files dovecot creates to be made accessible to the mail group. Please tell me this wasn't hard-coded a la postfix. Thanks, Kurt Fitzner Links: ------ [1] https://wiki.dovecot.org/MailboxFormat/Maildir#Maildir_and_filesystems [2] https://doc.dovecot.org/configuration_manual/protocols/lmtp_server/ [3] https://doc.dovecot.org/admin_manual/filesystem_permission/

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Issue with dovecot SASL
by Piyush Joshi 08 May '21

08 May '21

Hi, I am getting the following error while authenticating any user, using SASL with postfix, please help me to fix this issue. May 08 17:34:50 master: Info: Dovecot v2.2.36.4 (baf9232c1) starting up for imap, pop3, lmtp, sieve (core dumps disabled) May 08 17:35:10 master: Error: service(auth): command startup failed, throttling for 2 secs May 08 17:35:10 auth: Fatal: master: service(auth): child 6969 killed with signal 11 (core dumps disabled) *Dovecot Configuration Output* root@mail:/usr/local/dovecot/etc/dovecot/conf.d# /usr/local/dovecot/sbin/dovecot -n # 2.2.36.4 (baf9232c1): /usr/local/dovecot/etc/dovecot/dovecot.conf # Pigeonhole version 0.4.24.2 (aaba65b7) # OS: Linux 4.19.0-16-amd64 x86_64 Debian 10.9 # Hostname: mail.example.com auth_default_realm = example.com auth_mechanisms = plain login base_dir = /usr/local/dovecot/var/run/dovecot/ default_client_limit = 5000 default_process_limit = 500 default_vsz_limit = 512 M first_valid_uid = 1001 last_valid_uid = 1001 listen = 127.0.0.1 lmtp_save_to_detail_mailbox = yes log_path = /var/log/imap login_greeting = Messaging Server mail_gid = 1001 mail_location = maildir:/%Lh/Maildir/:INDEX=/%Lh/Maildir/ mail_plugins = quota acl fts fts_lucene mail_uid = 1001 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 vacation-seconds imapflags notify namespace inbox { inbox = yes location = mailbox Archive { auto = subscribe special_use = \Archive } mailbox "Deleted Items" { special_use = \Trash } mailbox Drafts { auto = subscribe special_use = \Drafts } mailbox Junk { auto = subscribe special_use = \Junk } mailbox "Junk E-mail" { special_use = \Junk } mailbox Sent { auto = subscribe special_use = \Sent } mailbox "Sent Items" { special_use = \Sent } mailbox Trash { auto = subscribe special_use = \Trash } prefix = separator = . type = private } passdb { args = /usr/local/dovecot/etc/dovecot/dovecot-ldap.conf.ext driver = ldap } plugin { acl = vfile:/usr/local/dovecot/dovecot-acl/acl acl_shared_dict = file:/maildir/domains/dovecot/shared-mailboxes/shared-mailboxes.db fts = lucene fts_autoindex = yes fts_lucene = whitespace_chars=@. fts_tika = http://localhost:9997/tika/ quota = maildir:User quota quota_rule = *:storage=1G quota_warning = storage=85%% quota-warning 85 %u quota_warning2 = storage=90%% quota-warning 90 %u quota_warning3 = storage=95%% quota-warning 95 %u sieve = ~/.dovecot.sieve sieve_after = /usr/local/dovecot/sieve/default.sieve sieve_before = ~/sieve/01_vacation.sieve sieve_dir = ~/sieve sieve_extensions = +notify +imapflags +vacation +vacation-seconds sieve_global_dir = /usr/local/dovecot/sieve/ sieve_quota_max_scripts = 5 sieve_vacation_send_from_recipient = yes sieve_vacation_use_original_recipient = yes } pop3_client_workarounds = outlook-no-nuls oe-ns-eoh protocols = imap pop3 lmtp sieve service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } unix_listener auth-userdb { group = vmail mode = 0666 user = vmail } } service imap-login { inet_listener imap { port = 143 } inet_listener imaps { address = * port = 993 ssl = yes } } service imap-postlogin { executable = script-login /usr/local/dovecot/bin/postlogin.sh user = root } service imap { executable = /usr/local/dovecot/libexec/dovecot/imap imap-postlogin } service lmtp { executable = lmtp -L inet_listener lmtp { address = 127.0.0.1 ::1 port = 7025 } process_min_avail = 5 unix_listener /var/spool/postfix/private/dovecot-lmtp { group = postfix mode = 0600 user = postfix } user = vmail } service managesieve-login { inet_listener sieve-obsolete { port = 2000 } } service pop3-login { inet_listener pop3 { port = 110 } inet_listener pop3s { address = * port = 995 ssl = yes } } service quota-warning { executable = script /usr/local/dovecot/bin/quota-warning.sh unix_listener quota-warning { group = vmail mode = 0660 user = vmail } } service stats { unix_listener stats-reader { group = vmail mode = 0660 user = vmail } unix_listener stats-writer { group = vmail mode = 0660 user = vmail } } ssl = required ssl_ca = </etc/ssl/localcerts/intermediate.crt ssl_cert = </etc/ssl/localcerts/mail.crt ssl_key = # hidden, use -P to show it submission_host = 127.0.0.1 userdb { args = /usr/local/dovecot/etc/dovecot/dovecot-ldap.conf.ext driver = ldap } protocol lmtp { mail_plugins = quota acl fts fts_lucene sieve } protocol sieve { managesieve_logout_format = bytes ( in=%i : out=%o ) } protocol lda { info_log_path = /var/log/dovecot-lda.log log_path = /var/log/dovecot-lda-errors.log mail_plugins = quota acl fts fts_lucene sieve virtual } protocol imap { mail_max_userip_connections = 50 mail_plugins = quota acl fts fts_lucene imap_quota imap_acl } Thanks, Regards

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Doveadm sync verbose not working?
by Plutocrat 07 May '21

07 May '21

Hi Was trying a sync with eg this. old is a host set up in my ssh config file. the user exists on both sides. The sync completes correctly copying mails back and forth, but offers no feedback. doveadm sync -u user(a)domain.com -f -R remote:old If I add -v I don't get any more information. Am I missing something? The manual says its meant to give more info and progress. doveadm -v sync -u user(a)domain.com -f -R remote:old Putting -v elsewhere on the commandline results in an error, so I think its in the right place. However -D works, but its a bit too verbose ... doveadm -D sync -u user(a)domain.com -f -R remote:old dovecot --version 2.3.7.2 (3c910f64b) P.

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Adding virtual folders to an existing dovecot installation
by Christian Wolf 06 May '21

06 May '21

Hello dear dovecot mailinglist, I am having a dovecot installation that is working so far (together with sieve and managesieve). Now, I found the possibility to add a virtual folder to the server promising. I sort various mails using a per-user sieve script into subfolders. This works well on the latop but the mobile device does not like too many folders to check. So, I wanted to create a virtual inbox that holds all unread messages. I found this documentation: https://doc.dovecot.org/configuration_manual/virtual_plugin/ Now, I have first one question: When I use the virtual folder and read a message/mark it as read, will this be reflected on the underlaying folder or will it cause trouble on dovecot? As far as I understand, usage of sieve filtering and the virtual plugin is considered critical as mentioned in the documentation. This is due to the fact, that the virtual mailboxes are read-only by default (unless a folder is prefixed with a !-symbol). Sieve will try to filter the virtual folder as well be default and moving a message to another folder will fail the read-only assumption. Honestly, I do not get the content of https://doc.dovecot.org/ configuration_manual/virtual_plugin/#sieve-filters-with-virtual-mailboxes by 100%. The first paragraph indicates that sieve plus virtual mailboxes are a complete no-go, while the second indicates that a safe configuration is needed. Could someone please elaborate this a bit more? I have not yet changed anything as I did not want blindly break my production mail system. The current (unaltered) configuration I will attach below. Bonus question: Is it possible to restrict the effect of the virtual plugin to certain (virtual) user accounts? Thank you very much Christian # dovecot --version 2.3.13 (89f716dc2) #dovecot -n # 2.3.13 (89f716dc2): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.13 (cdd19fe3) # OS: Linux 5.11.2-arch1-1 x86_64 # Hostname: server-hh.hh.lupus auth_mechanisms = plain login mail_location = maildir:~/Maildir 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 namespace inbox { 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 Templates { auto = subscribe } mailbox Trash { auto = subscribe special_use = \Trash } prefix = } passdb { args = scheme=PLAIN username_format=%n /home/.vmail/%d/etc/shadow driver = passwd-file } plugin { sieve = file:~/sieve;active=~/.dovecot.sieve stats_refresh = 30 secs stats_track_cmds = yes } protocols = imap lmtp sieve service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0660 user = postfix } } service stats { fifo_listener stats-mail { mode = 0600 user = vmail } } ssl = required ssl_cert = </etc/letsencrypt/live/dovecot/fullchain.pem ssl_cipher_list = ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM- SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA- AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128- SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128- SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256- SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS- AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256- SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128- SHA:AES256-SHA:AES:CAMELLIA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!RC4:! MD5:!PSK:!aECDH:!EDH-DSS-DES-CBC3-SHA:!EDH-RSA-DES-CBC3-SHA:!KRB5-DES-CBC3-SHA ssl_dh = # hidden, use -P to show it ssl_key = # hidden, use -P to show it ssl_prefer_server_ciphers = yes userdb { args = uid=vmail gid=vmail home=/home/.vmail/%d/mails/%n driver = static } protocol lmtp { mail_plugins = " sieve" postmaster_address = postmaster(a)example.com } protocol lda { mail_plugins = " sieve" } protocol imap { mail_plugins = " old_stats" }

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disable pop3 ports?
by Dan Egli 05 May '21

05 May '21

I admit I don't quite understand dovecot's config yet, but this is driving me batty. I was looking at my server and noticed that dovecot was listening on the pop3 ports (110/TCP). Since I do not use pop3 at all, nor does anyone who has ever or ever will connect to the server, that seems like a needless waste. So I went through the config files and commented out every reference to pop3 in them. But when I restart dovecot, it STILL opens a listener on 110. How do I fix this? The ONLY external ports I want dovecot listening to are imap4 and imap4s. Thanks! -- Dan Egli From my Test Server

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POP3 mailbox errors and changing permissions on folders
by John Richards 05 May '21

05 May '21

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