June 2023 - dovecot - dovecot.org

Re: No-novice with Dovecot, but need novice-like advice (was Dovecot cracked?!)
by Jochen Bern 10 Jun '23

10 Jun '23

On 09.06.23 00:36, Richard Troy wrote: > OH, sure, I got it down to a trickle, but these few Russian sites > always managed to get their spam through and (FWIW, if you can characterize the offenders by country, trying a GeoIP filter as a stop-gap measure sounds rather promising.) > Give me a white-list of the > ONLY accounts that can relay; NOTHING ELSE can relay. ... THAT would do > it! But no! Neither in Postfix nor dovecot is there such a thing! I'm afraid that that's not *entirely* true ... : > /etc/postfix# grep senderauth main.cf > smtpd_sender_login_maps = hash:/etc/postfix/senderauth > /etc/postfix# head -2 senderauth ; grep bern senderauth | sed -e 's/[-a-z\.]*'"$DOMAIN/DOMAIN/g" > # Envelope Sender: Requires SMTP AUTH as one of: > # actual.address(a)dom.ain user.1(a)dom.ain, another(a)else.where > jochen.bern(a)DOMAIN.pawisda.de jochen.bern(a)DOMAIN.de (Also works with unspecified local part, i.e., "@some.dom.ain" for the left-hand side.) > Combine that with a greylist type function where the usual IP addresses > for particular users were let through, and new ones delayed, THAT would > be awesome, too! Please define "delayed". The kind where you tell the client to retry later and then close the connection is available for postfix under the name of postgrey, but is probably quite disruptive when used with an M*S*A port; same caveat for mechanisms that prevent the connection altogether, like one could build with iptables. The search keyword for the kind where "the server is just deeaaaaaaadddd slllooooowwwww" would be "Teergrube". [Yes, I'm German, so I capitalize German nouns like German does. :-> ] None of those are *built right into* postfix or dovecot, likely because it's too much complexity to maintain for a huge user base that doesn't use the functionality all too often. > And if someone tells me I'm wrong and points me at how to do these > things, I'll fall out of my damned chair! [promptly invents the sport of Comfy Cushion Curling] > IF we had an IMAP supported password CHANGING scheme, we'd gladly run > encrypted passwords, but there isn't, and we haven't invented (finished > inventing!) our own web-way to change 'em and so we're stuck with plain > text until one of these things changes. Your server is Linux and SSH client software has become quite available (PuTTY on Windows). For OS-based users who don't need *shell* access to the server, I've had some success just setting the "passwd" command as their login "shell" (in /etc/passwd . Plus adding it to /etc/shells if necessary.) Dunno how readily you could find an equivalent for the *virtual* accounts' password backend ... (Yes, it'd be better to have it seamlessly integrated into the IMAP protocol, but don't forget that you'd need the *MUAs* to start supporting it as well before the general public will ever even learn about the new feature ...) Kind regards, -- Jochen Bern Systemingenieur Binect GmbH

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No-novice with Dovecot, but need novice-like advice (was Dovecot cracked?!)
by Richard Troy 09 Jun '23

09 Jun '23

Hi All, This is my first posting here, and maybe I should have found this WAY back in January, '23, if not LONG before. I want to be but I find it difficult here to be brief. ... Surely background will surely help: A 27 or so year old Fedora / Postfix / Dovecot site I built had a major disaster in January and I've not yet been able to fully recover because Dovecot has let the damned spammers in again and again and again and again! OH, sure, I got it down to a trickle, but these few Russian sites always managed to get their spam through and I just had to shut Dovecot down entirely. I never found out how they got in, etc. And I've STRONGLY suspected Dovecot got cracked - at least the modern version in the youngest version for the youngest Fedora we had back in January - uh, Fedora Server 37 - I've forgotten the matching Dovecot version. In the disaster, we lost /var but not /etc, so I figured recovery would be easy and for nearly everything, it was. But NOT Dovecot (and insofar as it matters, Postfix), and in these 5+ months I've tried so many things, I'm sure I've forgotten most of them and I don't know that a retroactive look is worth doing. ...I kept some notes that might be useful if anyone wants to see the evidence of the cracking, but in short, I kept a constant watch on the logs and when ANY relay happened that shouldn't, I'd instantly know it and shut things off entirely. However, that became untenable as I couldn't find the problem and had to just shut it off, pissing off users, etc, but I've had to do things like spend a month and a half traveling, and so forth and, well... Life goes on, as the saying goes. --- NOW I want to try again. It's my perception that it's a waste of time to even LOOK at the old Dovecot configuration stuff. I feel I need to REMOVE it ALL, and I could use some help being SURE to get it all gone. And then I think I need to do a FULL new installation. Overkill? IDK. I could use some advice about SAFE ways to make changes and test to ensure we do NOT become an open mail relay EVER AGAIN. ALSO WORTH SAYING is that if Dovecot were all that damned safe and secure I wouldn't so easily be able to propose a new feature that would make a HUGE difference to sites like mine: Give me a white-list of the ONLY accounts that can relay; NOTHING ELSE can relay. ... THAT would do it! But no! Neither in Postfix nor dovecot is there such a thing! Combine that with a greylist type function where the usual IP addresses for particular users were let through, and new ones delayed, THAT would be awesome, too! And this isn't even all that hard to do - I could do it if I didn't already have a thousand obligations in life! And if someone tells me I'm wrong and points me at how to do these things, I'll fall out of my damned chair! And after picking myself up, I'll find a way to send that person some sort of gift. THIS WOULD HAVE SOLVED ALL MY PROBLEMS. And I'm sure MANY others could use this, too! --- THIS configuration: I'd like to find a way to have both virtual and our existing "unix accounts" users. IF we had an IMAP supported password CHANGING scheme, we'd gladly run encrypted passwords, but there isn't, and we haven't invented (finished inventing!) our own web-way to change 'em and so we're stuck with plain text until one of these things changes. BTW, isn't this a HUGE and OBVIOUS hole that should have been fixed decades ago?! If a major provider like the Dovecot.org team added a way to update passwords to the IMAP protocol, all the rest of the folks would follow along for sure! OR, "is that a thing" and I'm just ignorant of it? So, again, plain-text, in cram, of course. What else? Coach me on "the right way" if you want, but if users can't change it themselves, they'd rather I can retrieve it for them if needed... I'm sure the corporate world doesn't do it this way, but their code isn't open source, or am I wrong?... --- In closing I don't actually anticipate ANY help. My father, an even earlier computer user than me, once observed, "you can ask for information until you're blue in the face, and nobody will say a thing, but post the WRONG thing and a hundred people will post to point out you're wrong!" GIVEN how EASY it is to have your email system become an instant open relay at the hands of the spammers out there, how the hell Dovecot can advertise the way it is WITHOUT a serious guide about this is just frustrating and laughable. But I'd love to be shown where they DO help with this! Thanks for any and all help, Richard

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Remove attachments
by Oliver Glas 08 Jun '23

08 Jun '23

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Help needed with imap_sieve and mail_crypt plugin
by Robert Senger 08 Jun '23

08 Jun '23

Hi there, I was using imap_sieve for many years now to pipe mails upon user action (moving mails to the SPAM folder) into spamassassin to train spam detection. This worked fine all the time. Now we're moving to encrypted mail storage on per user basis, with encrypted private keys. This works well, but it breaks the spamassassin training upon user action since it would feed encrypted mail into spamassassin, which makes no sense. So, my question is, is there a possibility to call the mail_crypt plugin from imap_sieve to decrypt the email (that means, decrypt the private key with the user password, decrypt the email that's moved to the SPAM folder) before it's piped into spamassassin? Thanks for help! Robert -- Robert Senger

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Repeating imap processes crashes with signal 11 after imapc-client timeout leak
by Nikolaos Pyrgiotis 07 Jun '23

07 Jun '23

Hello, We run a 5 instances dovecot cluster ondebian 11 virtual machines, a dovecot proxy, 2directors and 2dovecot backends. All dovecot instances run version 2.3.20. We use a glusterfs mounted volume on the backends forthe mail storage. Our users all use thunderbird mail client and they do not report any issue with the imap service. Since we have configured the dovecot cluster we see multiple random imap crashes with signal 11 and timeout leaks in the logs on both the backends for multiple users. Is this is a configuration problem or a bug with imapc or imap; I would appreciate if you could assist us to debug this further. A coredump is attached if it helps. The logs look similar to this: Jun 01 16:21:13 doveb0-rmt0-cn1 dovecot[75106]: imap(user(a)domie02.com)<105800><BxSqJw39DLgKZQD+>: Warning: Timeout leak: 0x7f9a92c0c1c0 (imapc-client.c:475) Jun 01 16:21:13 doveb0-rmt0-cn1 dovecot[75106]: imap(user(a)domie02.com)<105800><BxSqJw39DLgKZQD+>: Warning: Raw backtrace for leaks: /usr/lib/dovecot/libdovecot.so.0(backtrace_append+0x42) [0x7f9a92a7e872] -> /usr/lib/dovecot/libdovecot.so.0(backtrace_get+0x1e) [0x7f9a92a7e98e] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_destroy+0x2b5) [0x7f9a92aa21e5] -> /usr/lib/dovecot/libdovecot-storage.so.0(imapc_client_run+0x115) [0x7f9a92c0bcb5] -> /usr/lib/dovecot/libdovecot-storage.so.0(imapc_mailbox_run_nofetch+0x20) [0x7f9a92c089f0] -> /usr/lib/dovecot/libdovecot-storage.so.0(imapc_mailbox_sync_init+0x868) [0x7f9a92c0b198] -> /usr/lib/dovecot/libdovecot-storage.so.0(mailbox_sync_init+0x58) [0x7f9a92bbfa68] -> dovecot/imap(imap_sync_init+0x95) [0x5605e4ebbe55] -> dovecot/imap(+0x17343) [0x5605e4ea5343] -> dovecot/imap(cmd_idle+0xb4) [0x5605e4ea5674] -> dovecot/imap(command_exec+0xa4) [0x5605e4eb04d4] -> dovecot/imap(+0x2044f) [0x5605e4eae44f] -> dovecot/imap(+0x204fa) [0x5605e4eae4fa] -> dovecot/imap(client_handle_input+0x1b5) [0x5605e4eae9d5] -> dovecot/imap(client_input+0x70) [0x5605e4eaef40] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_call_io+0x69) [0x7f9a92aa1819] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run_internal+0x132) [0x7f9a92aa2f02] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_handler_run+0x50) [0x7f9a92aa18c0] -> /usr/lib/dovecot/libdovecot.so.0(io_loop_run+0x40) [0x7f9a92aa1a80] -> /usr/lib/dovecot/libdovecot.so.0(master_service_run+0x13) [0x7f9a92a143c3] -> dovecot/imap(main+0x4fa) [0x5605e4e9ff0a] -> /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xea) [0x7f9a927d2d0a] -> dovecot/imap(_start+0x2a) [0x5605e4e9ffca] Jun 01 16:23:49 doveb0-rmt0-cn1 dovecot[75106]: imap(user(a)domie02.com)<105800><BxSqJw39DLgKZQD+>: Fatal: master: service(imap): child 105800 killed with signal 11 (core dumped) Below i post the dovecot configuration of one of the two dovecot backends: # 2.3.20 (80a5ac675d): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.20 (149edcf2) # OS: Linux 5.10.0-23-amd64 x86_64 Debian 11.7 fuse.glusterfs # Hostname: doveb0-rmt0-cn1 auth_cache_negative_ttl = 5 mins auth_cache_size = 50 M auth_default_realm = domie02.com auth_master_user_separator = * auth_mechanisms = plain login auth_verbose = yes auth_worker_max_count = 16 disable_plaintext_auth = no first_valid_uid = 499 hostname = smtp.domie02.com imapc_features = fetch-bodystructure fetch-headers rfc822.size search modseq acl delay-login imapc_host = 10.101.0.250 imapc_max_idle_time = 5 mins imapc_password = # hidden, use -P to show it imapc_sasl_mechanisms = plain login imapc_ssl = starttls imapc_ssl_verify = no last_valid_uid = 499 lda_mailbox_autocreate = yes lda_mailbox_autosubscribe = yes login_greeting = You have successfully logged in to domie02.com IMAP server login_trusted_networks = 10.101.0.74 10.101.0.73 mail_always_cache_fields = flags hdr.* date.received date.sent mail_cache_fields = flags date.received guid size.physical size.virtual imap.bodystructure body.snippet mail_debug = yes mail_fsync = always mail_location = mdbox:/var/vmail/%d/%n/mdbox:VOLATILEDIR=/dev/shm/dovecot/%2.256Nu/%d/%n mail_plugins = " notify mail_log zlib acl" mail_privileged_group = mail 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 mdbox_rotate_size = 200 M mmap_disable = yes namespace Domie02 { list = children location = imapc:/var/vmail/%d/%n/shared/indexes/%%n:INDEXPVT=/var/vmail/%d/%n/shared-pvt/%%n:VOLATILEDIR=/dev/shm/dovecot/%2.256Nu/%d/%n/%%n prefix = shared.%%n. separator = . subscriptions = no type = shared } namespace inbox { inbox = yes location = mailbox Drafts { special_use = \Drafts } mailbox Junk { special_use = \Junk } mailbox Sent { special_use = \Sent } mailbox "Sent Messages" { special_use = \Sent } mailbox Spam.Virus { auto = subscribe } mailbox Spam { auto = subscribe } mailbox Trash { special_use = \Trash } prefix = separator = . subscriptions = yes type = private } passdb { args = password=#hidden_use-P_to_show# driver = static master = yes override_fields = allow_real_nets=127.0.0.0/8,local,10.101.0.74,10.101.0.73 userdb_acl_user=%{auth_user} userdb_namespace/Domie02/disabled=yes result_success = continue } passdb { args = password=#hidden_use-P_to_show# driver = static override_fields = allow_real_nets=127.0.0.0/8,local,10.101.0.74,10.101.0.73 result_success = continue } passdb { args = /etc/dovecot/dovecot-ldap-users.conf.ext driver = ldap } passdb { args = /etc/dovecot/dovecot-ldap-groups.conf.ext driver = ldap } plugin { acl = vfile:/etc/dovecot/global-acls/%d/master-dovecot-acl:cache_secs=300 acl_defaults_from_inbox = yes acl_globals_only = no acl_shared_dict =file:/var/dovecot-acl/%d/shared-mailboxes.db imap_compress_deflate_level = 6 mail_log_events = flag_change mail_log_fields = uid box flags sieve =file:~/sieve;active=~/sieve/%n.sieve sieve_before = /var/vmail/global-sieve/global.sieve sieve_env_email_address = %u sieve_env_mailbox_prefix = %{userdb:mailbox_prefix} sieve_global = /var/vmail/sieve sieve_global_extensions = +editheader +vnd.dovecot.environment zlib_save = zstd zlib_save_level = 5 } protocols = " imap lmtp sieve submission" service auth-worker { user = dovecot } service auth { unix_listener auth-userdb { group = mail mode = 0666 user = vmail } } service doveadm { inet_listener dovadm-dom-mgmt { address = 10.100.1.71 port = 8080 ssl = no } inet_listener dovadm-dom { address = 10.101.0.71 port = 8080 ssl = no } vsz_limit = 256 M } service imap-login { inet_listener imap-dom { address = 10.101.0.71 port = 143 ssl = no } inet_listener imap { port = 0 } inet_listener imaps-dom { address = 10.101.0.71 port = 993 ssl = yes } inet_listener imaps { port = 0 } process_limit = 400 process_min_avail = 2 service_count = 20 vsz_limit = 512 M } service imap { process_limit = 2048 process_min_avail = 0 service_count = 1 vsz_limit = 4 G } service lmtp { inet_listener lmtp-dom { address = 10.101.0.71 port = 24 ssl = no } process_limit = 0 process_min_avail = 0 service_count = 0 unix_listener lmtp { mode = 0666 } vsz_limit = 256 M } service managesieve-login { inet_listener sieve-dom { address = 10.101.0.71 port = 4190 ssl = no } inet_listener sieve { port = 0 } process_limit = 0 process_min_avail = 0 service_count = 0 vsz_limit = 64 M } service managesieve { process_limit = 1024 process_min_avail = 0 service_count = 1 vsz_limit = 256 M } service submission-login { inet_listener submission-dom { address = 10.101.0.71 port = 587 ssl = no } inet_listener submission { port = 0 } inet_listener submissions-dom { address = 10.101.0.71 port = 465 ssl = yes } process_limit = 250 process_min_avail = 2 service_count = 1 vsz_limit = 256 M } service submission { process_limit = 1024 process_min_avail = 0 service_count = 1 vsz_limit = 256 M } ssl = required ssl_cert = </etc/ssl/certs/doveb0-rmt0-cn1.mail.rmt.domie02.com.pem ssl_client_ca_dir = /etc/ssl/certs ssl_key = # hidden, use -P to show it submission_max_mail_size = 30000 k submission_relay_host = 10.101.0.7 submission_relay_port = 587 submission_relay_ssl = starttls submission_relay_ssl_verify = no submission_relay_trusted = yes userdb { driver = prefetch } userdb { args = /etc/dovecot/dovecot-ldap-users.conf.ext driver = ldap } userdb { args = /etc/dovecot/dovecot-ldap-groups.conf.ext driver = ldap } protocol lmtp { mail_plugins = " notify mail_log zlib acl sieve acl" } protocol lda { mail_plugins = " notify mail_log zlib acl sieve acl" } protocol imap { mail_max_userip_connections = 100 mail_plugins = " notify mail_log zlib acl" } protocol sieve { mail_max_userip_connections = 40 } protocol submission { mail_max_userip_connections = 70 } local 10.101.0.71 { doveadm_allowed_commands = doveadm_password = # hidden, use -P to show it } local 10.100.1.71 { doveadm_allowed_commands = doveadm_password = # hidden, use -P to show it } } Thank you, Nikolaos Pyrgiotis

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sieve accepting instructions from email
by Marc 07 Jun '23

07 Jun '23

Before switching to sieve, I used to have something in procmail that would allow you to turn on an auto reply by sending an email. - send email to yourself with request - receive auth code - send auth code and auto reply text - receive confirmation the auto reply is on Is there some solution in sieve (plugin) to configure your sieve rules via such email commands?

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Multiple backends with NFSv4.1 (supports file locking): should work without Director, right?
by pierre.alletru＠gmail.com 05 Jun '23

05 Jun '23

Hi Dovecot community, We're looking at running multiple Dovecot backend servers in parallel, all using the same shared NFSv4.1 mount to store mailboxes in the maildir format. We've read in multiple places that running multiple backends with a shared NFS can result in issues like index files corruption. The standard solution seems to use the Director feature, or some kind of IP based proxy/load balancer. But: 1 - The Director feature will be removed in future free versions of Dovecot (https://dovecot.org/mailman3/archives/list/dovecot@dovecot.org/thread/ILA3C…) 2 - NFSv4 and above support file locking (flock and fcntl, flock being emulated using fcntl). 3 - It looks like Dovecot does use file locking, though we're unsure if it does on everything and in particular on index files. Thus, we are wondering if the need for Director is still relevant with NFSv4? Shouldn't it work without Director thanks to file locking? Has anyone tried it? We're thinking that the documentation and various threads on the subject may be outdated, based on NFSv3 and lower (no file locking). If it doesn't work, anybody knows why? Isn't file locking there precisely to handle concurrency? Thanks!

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attachments storage sub folders
by cor＠soverin.net 04 Jun '23

04 Jun '23

Hi all, we're using a separate attachment storage. Is there a way to control the subfolders that are created for each attachment? Currently the path is <user subfolder>/XX/YY/XXYY<hash>. In practice this means almost every single attachment gets its own 2 subfolders XX/YY. I'm seeing users with 5000 attachments and almost 10.000 folders. Normally this wouldn't be that big of a deal but we're using ZFS storage with metadata special device and this is causing a huge amount of additional folder metadata. It would already be helpful if we could just have a single XX/XX<hash> subfolder per user. Is that possible? Thanks, Cor dovecot 2.3.20 mail_attachment_dir = /data/attachments/%{userdb:folder} mail_attachment_fs = posix mail_attachment_hash = %{sha256:160} mail_attachment_min_size = 128k

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Share
by liecj3＠bfh.ch 01 Jun '23

01 Jun '23

Hello dear Dovecot users I have a somewhat special request: I have a single file in mbox format which I want to make accessible via IMAP to anonymous logins. The mbox file is being updated outside of Dovecot and should not be changeable by Dovecot. So far I created a Docker container based on the official image (https://hub.docker.com/r/dovecot/dovecot) and configured the Dovecot according to https://doc.dovecot.org/configuration_manual/shared_mailboxes/public_shared/. The volume with the mbox file is mounted in the running container under /var/mail. Each time a client tries to access this public mailbox the following error is logged and no content is returned: May 26 21:57:06 imap(mutt)<16><Rkpg0Z/8pLfAqDAB>: Error: Mailbox Public/archive: open() failed with mbox: Read-only file system. Note that I don't need the file to be a shared mailbox. Instead I would also be happy to have all (anonymous) users mapped to the read-only mbox somewhere in the filesystem. Dockerfile: FROM dovecot/dovecot RUN mkdir -p /var/indexes/public RUN chown 1000:1000 /var/indexes/public ADD dovecot.conf /etc/dovecot/dovecot.conf /etc/dovecot/dovecot.conf: ## You should mount /etc/dovecot if you want to ## manage this file mail_home=/srv/mail/%Lu mail_location=sdbox:~/Mail mail_uid=1000 mail_gid=1000 #protocols = imap pop3 submission sieve lmtp protocols = imap first_valid_uid = 1000 last_valid_uid = 1000 passdb { driver = static args = password=pass } ssl=yes ssl_cert=<cert.pem ssl_key=<key.pem namespace { type = private inbox = yes separator = / } namespace { type = public prefix = Public/ location = mbox:/var/mail/:INDEX=/var/indexes/public subscriptions = no } listen = * log_path=/dev/stdout info_log_path=/dev/stdout debug_log_path=/dev/stdout

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Using "forward_" variables in last_login_key
by Eirik Rye 01 Jun '23

01 Jun '23

Hello, In my setup, I am running dovecot with the following last_login config: plugin { last_login_dict = file:~/.last_login last_login_key = %s } I would like to distinguish between logins through webmail (Roundcube) and logins through regular IMAP clients. Roundcube sends "x-forward-service=webmail" in ID, and I have working logging for this by putting the following in login_log_format_elements: service=%{if;%{passdb:forward_service};eq;webmail;webmail;%s} (Is there may be a more elegant way to do this conditional?) This will print `service=webmail` for webmail logins, and `service=imap` for regular IMAP client logins. However, the same conditional does not work in last_login_key: last_login_key = %{if;%{passdb:forward_service};eq;webmail;webmail;%s} Using this, the login fails and the error log outputs the following error: Error: Failed to expand plugin setting last_login_key = '%{if;%{passdb:forward_service};eq;webmail;webmail;%s}': Unknown variable '%passdb' How can I tell which variables are available to use in this plugin? Are the forwarded variables not available? If not, any other suggestions on how to differentiate these logins in last_login? Looking at the remote_ip is not feasible for my setup. Best regards, Eirik

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