- dovecot - dovecot.org

NFC normalization rename errors after 2.3 to 2.4 upgrade (mdbox)
by Jan Münnich 16 May '26

16 May '26

Hi, We just upgraded from 2.3 to 2.4.3 and are now getting errors like this for any mailbox with German umlauts in the name: "Error: Failed to rename mailbox 'Anträge' for NFC normalization: Mailbox doesn't exist: Anträge" The mailboxes work fine otherwise, doveadm mailbox status shows them with correct message counts. The errors show up on IMAP access but don't seem to break anything. We're using mdbox. On disk the directory is stored as mUTF-7: Antr&AOQ-ge doveadm mailbox list gives back the name with c3 a4 for the ä, which is already NFC. We double-checked with python3 unicodedata and it confirms the name is NFC. So it seems like dovecot is trying to rename something that doesn't need renaming, and then failing. Is there a way to turn off this automatic rename? Or is this a known issue with mdbox and mUTF-7 directory names? Any help would be appreciated to find out if this is a bug or a configuration issue on our side! Thanks, Jan

3 3

Regression/Bug report: crypt_private_key_file (for crypt_global_private_key) no longer supports inline base64 (from userdb) in dev branch
by Ömer Güven 15 May '26

15 May '26

Hi, I’ve run into what appears to be a regression (or at least a behavioral change) in Dovecot 3.3.0+ / current HEAD regarding crypt_private_key_file handling for the crypt_global_private_key. I don‘t use per-folder user keys but a global encryption key per user. Previously, it was possible to provide the private key via userdb using an inline base64:-encoded PEM directly to the crypt_global_private_key_file and Dovecot would correctly parse and use it. With the latest config scheme change, this no longer works, as you cannot really set named config variables from userdb. I did workaround by setting a custom userdb variable and setting the needed named/filter variables manually in the config file. To make it work, I had to enclose the config in a „protocol imap“ scope. The crypt_global_public_key_file is accessible from userdb (as it is not within a named filter scope), so inline-base64 works as with Dovecot 2.3+. When using the following workaround to reach the scoped variables, Dovecot tries to load the file „inline:BASE64ENCODEDPEM“ as a literal filename (error open(inline:AB….C==) failed): protocol imap { crypt_global_private_key user { crypt_private_key_file = %{userdb:private_key_file} crypt_private_key_password = %{userdb:private_key_password} } } As a workaround, I now have to: • store the private key as a file (e.g. %{home}/privkey.pem) • pass only the password via userdb • inject the path indirectly via static config + userdb variables This works, but is less elegant: protocol imap { crypt_global_private_key user { crypt_private_key_file = %{home}/privkey.pem crypt_private_key_password = %{userdb:private_key_password} } } Again, with the new named filter mechanism, it’s no longer possible to directly inject such config values via userdb, which makes fully dynamic per-user key provisioning harder. I now have to export all encrypted private keys from the database to the users home directory. Ömer Hi, I've run into what appears to be a regression (or at least a behavioral change) in Dovecot 3.3.0+ / current HEAD regarding crypt_private_key_file handling for the crypt_global_private_key. I don`t use per-folder user keys but a global encryption key per user. Previously, it was possible to provide the private key via userdb using an inline base64:-encoded PEM directly to the crypt_global_private_key_file and Dovecot would correctly parse and use it. With the latest config scheme change, this no longer works, as you cannot really set named config variables from userdb. I did workaround by setting a custom userdb variable and setting the needed named/filter variables manually in the config file. To make it work, I had to enclose the config in a "protocol imap" scope. The crypt_global_public_key_file is accessible from userdb (as it is not within a named filter scope), so inline-base64 works as with Dovecot 2.3+. When using the following workaround to reach the scoped variables, Dovecot tries to load the file "inline:BASE64ENCODEDPEM" as a literal filename (error open(inline:AB....C==) failed): protocol imap { crypt_global_private_key user { crypt_private_key_file = %{userdb:private_key_file} crypt_private_key_password = %{userdb:private_key_password} } } As a workaround, I now have to: o store the private key as a file (e.g. %{home}/privkey.pem) o pass only the password via userdb o inject the path indirectly via static config + userdb variables This works, but is less elegant: protocol imap { crypt_global_private_key user { crypt_private_key_file = %{home}/privkey.pem crypt_private_key_password = %{userdb:private_key_password} } } Again, with the new named filter mechanism, it's no longer possible to directly inject such config values via userdb, which makes fully dynamic per-user key provisioning harder. I now have to export all encrypted private keys from the database to the users home directory. Oemer

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Panic: file charset-iconv.c: line 83 (charset_to_utf8_try): assertion failed: (srcleft <= CHARSET_MAX_PENDING_BUF_SIZE)
by Alex Rosenberg 15 May '26

15 May '26

Attached is an LLM-reduced reproduction of the crash in the title. My particular setup is dovecot 2.3.21.1 (d492236fa0) in a FreeBSD jail (13.5). I realize that this is an older release but there is no FreeBSD port/pkg for dovecot 2.4.x yet. The message in the attachment is reduced from an old (2017!) email to one of the LLVM compiler mailing lists. The original malformed email had this header: X-Mailer: Evolution 3.22.5 (3.22.5-1.fc25) The bug occurs when dovecot's FTS indexer processes a MIME part that: 1. Declares charset="UTF-7" 2. Contains base64-encoded content that, when decoded, has bare '+' characters 3. Causes UTF-7 decoder buffer overflow in charset-iconv.c:83 The base64 content decodes to C source code with expressions like: - argc + 4 - state++ - state-- These '+' characters in UTF-7 context cause the decoder's pending buffer to exceed CHARSET_MAX_PENDING_BUF_SIZE, triggering the assertion failure. Alex

4 5

flatcurve index size (10x larger than lucene)
by Jean-Daniel Beaubien 14 May '26

14 May '26

Hi everyone, I am currently trying to update from an old dovecot 2.3 setup with fts-lucene to 2.4.2 with fts-flatcurve. However, I am seeing a giant jump in the size of the indexes. For an email account that takes 12GB of storage, I get the following index sizes: - lucene: 270 MB - flatcurve: 2400 MB That is almost a 10x increase in the index size (with flatcurve the indexes represent 20% of the size of the mailbox). Considering I have a mailbox that takes 270GB, I can't imagine the size of the indexes. *Am I doing something wrong with flatcurve? How can the indexes be so much larger than lucene?* I took the default flatcurve configuration from the Ubuntu 26.04 install: mail_plugins { fts = yes fts_flatcurve = yes } fts_autoindex = yes language_filters = normalizer-icu snowball stopwords language_tokenizers = generic email-address language_tokenizer_generic_algorithm = simple language en { default = yes filters = lowercase snowball english-possessive stopwords } fts flatcurve { # All of these are optional, and indicate the default values. # They are listed here for documentation purposes; most people should not # need to define/override in their config. # commit_limit = 500 # max_term_size = 30 # min_term_size = 2 # optimize_limit = 10 # rotate_count = 5000 # rotate_time = 5000 substring_search = yes } *Any help/insight would be greatly appreciated.* Best regards, -J Hi everyone, I am currently trying to update from an old dovecot 2.3 setup with fts-lucene to 2.4.2 with fts-flatcurve. However, I am seeing a giant jump in the size of the indexes. For an email account that takes 12GB of storage, I get the following index sizes: o lucene: 270 MB o flatcurve: 2400 MB That is almost a 10x increase in the index size (with flatcurve the indexes represent 20% of the size of the mailbox). Considering I have a mailbox that takes 270GB, I can't imagine the size of the indexes. Am I doing something wrong with flatcurve? How can the indexes be so much larger than lucene? I took the default flatcurve configuration from the Ubuntu 26.04 install: mail_plugins { fts = yes fts_flatcurve = yes } fts_autoindex = yes language_filters = normalizer-icu snowball stopwords language_tokenizers = generic email-address language_tokenizer_generic_algorithm = simple language en { default = yes filters = lowercase snowball english-possessive stopwords } fts flatcurve { # All of these are optional, and indicate the default values. # They are listed here for documentation purposes; most people should not # need to define/override in their config. # commit_limit = 500 # max_term_size = 30 # min_term_size = 2 # optimize_limit = 10 # rotate_count = 5000 # rotate_time = 5000 substring_search = yes } Any help/insight would be greatly appreciated. Best regards, -J

3 2

Can't find unicode/ustring.h in test
by mr.thesaw＠gmail.com 14 May '26

14 May '26

I get this error during compilation: make[3]: Entering directory '/home/hacksaw/src/dovecot-2.4.4/src/lib-language' CC test-lang-icu.o In file included from test-lang-icu.c:8: lang-icu.h:4:10: fatal error: unicode/ustring.h: No such file or directory 4 | #include <unicode/ustring.h> | ^~~~~~~~~~~~~~~~~~~ compilation terminated. I have unicode 66, at least as far as Ubuntu is concerned.

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Dovecot 2.4.4 - mail_crypt with per-user Global Keys from LDAP (not Folder Keys)
by luis.neapolis＠gmail.com 14 May '26

14 May '26

Hi everyone, I'm trying to configure Dovecot 2.4.4 with per-user encryption keys stored in LDAP, using Global Keys mode (NOT Folder Keys). My goal: Each user has their own public key and private key (encrypted with the user's login password) stored in LDAP attributes. 1) LMTP should use the public key to encrypt incoming emails. 2) IMAP should use the user's login password to decrypt the private key from LDAP, then decrypt the emails. I want to use Global Keys mode (where keys are provided via userdb), NOT Folder Keys (where Dovecot stores keys in dovecot-attributes files). What works: LMTP receives emails and encrypts them correctly using the user's public key from LDAP and the encrypted files are saved to disk. What doesn't work: IMAP can log in and see the email list (subject, from, date), but the email body never loads. Error: Decryption error: no private key available May 14 18:58:45 host dovecot[295725]: imap(test(a)example.com)<295760><SESSIONID>: Debug: Mailbox INBOX: UID 11: Opened mail because: prefetch May 14 18:58:45 host dovecot[295725]: imap(test(a)example.com)<295760><SESSIONID>: Debug: dict(file): Looking up 'priv/a82ea60599ba056ad47904003a5aeee9/vendor/vendor.dovecot/pvt/crypt/privkeys/aacbcb614fb59f81e9519186b12ac8862858d89fa3bcc1be5f25b886d3e95ee3' May 14 18:58:45 host dovecot[295725]: imap(test(a)example.com)<295760><SESSIONID>: Debug: dict(file): Lookup finished for 'priv/a82ea60599ba056ad47904003a5aeee9/vendor/vendor.dovecot/pvt/crypt/privkeys/aacbcb614fb59f81e9519186b12ac8862858d89fa3bcc1be5f25b886d3e95ee3': not found May 14 18:58:45 host dovecot[295725]: imap(test(a)example.com)<295760><SESSIONID>: Error: Mailbox INBOX: UID 11: read() failed: read(/mail/example.com/test/cur/1778773528.M279604P294174.host.example.com,… failed: Decryption error: no private key available (FETCH BODY[1]) The confusing part: IMAP has the user's password (the user authenticated successfully). The private key in LDAP is encrypted with that same password. So IMAP should be able to decrypt the private key, then decrypt the email. But Dovecot is not using the password it already has to unlock the private key. My configuration: dovecot_config_version = 2.4.4 mail_plugins { quota = yes } # Empty global key block (workaround for LMTP not to fail) crypt_global_private_key main { } passdb ldap { driver = ldap filter = (&(objectClass=Account) (mail=%{user})) fields { mail = %{ldap:mail} password = %{ldap:userPassword} userdb_home = %{ldap:homeDirectory} } } userdb ldap { driver = ldap filter = (&(objectClass=Account) (mail=%{user})) fields { home = %{ldap:homeDirectory} uid = %{ldap:uidNumber|default('500')} gid = %{ldap:gidNumber|default('500')} # Per-user keys from LDAP (Global Keys mode) crypt_global_public_key_file = inline:%{ldap:userPublicKey} crypt_global_private_key/main/crypt_private_key_file = inline:%{ldap:userPrivateKey} crypt_private_key_password = %{password} } } protocol imap { mail_plugins { imap_quota = yes mail_crypt = yes } protocol lmtp { mail_plugins { sieve = yes mail_crypt = yes } } Note: I do NOT have mail_attribute_dict configured. I do NOT want Dovecot to store keys in local files. I want everything to come from LDAP. What I've verified: 1) The private key is valid and decrypts correctly with the user's password using openssl pkey -passin pass:xxx. 2) doveadm user shows the keys are retrieved from LDAP. The error persists. The question: Since IMAP already has the user's password (from the successful login), how can I make Dovecot use that password to decrypt the private key from LDAP and then decrypt the emails? Is there a specific setting I'm missing? Does crypt_private_key_password = %{password} need to be placed somewhere else (e.g., inside the protocol imap block) to work correctly? Also, I see in the logs that Dovecot is still looking for dict(file) keys (Folder Keys mode). How can I completely disable Folder Keys behavior and force Dovecot to only use Global Keys from LDAP? Thank you! Dovecot version: 2.4.4-5 OS: AlmaLinux 9.7 Mail storage: Maildir

1 0

Dovecot 2.4 authentication
by David Koski 14 May '26

14 May '26

Hello, I just put a new Postfix with Dovecot 2.4 server on line migrating the email from Dovecot 2.3. I have discovered a number of clients (all copiers so far) that no longer authenticate SMTP. Mechanisms configured: auth_mechanisms = plain login gssapi cram-md5 digest-md5 I found that if I disable all encrypted password methods (some copiers list them separately with a checkbox) and leave only plain/login on the client side, then it succeeds. But sometimes it is not necessary. It's almost as if it only tries once and gives up if it fails. I'm not sure how it is actually supposed to work. But it worked with Dovecot 2.3. I did test one account with an encrypted password like "{CRAM-MD5}6e3..." successfully. But other accounts failed. It almost looks like the encryption method must be specified on the client side to match the server before it will work consistently. I know that password encryption is unnecessary with STARTTLS but I have to live with it now. I have noticed that Thunderbird configured with encryption silently falls back to plain/login so I didn't notice a problem. Regards, David Koski dkoski(a)sutinen.com

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Backup problem
by Doug Hardie 13 May '26

13 May '26

I just migrated my mail server to a new machine. When the new machine was back up and running, I found one mailbox that used to have many emails, now only had 3. I went back to the old machine and found there were only those three messages in the mailbox. I suspect somehow I managed to delete them prior to the backup to the new machine. I have a copy of that mailbox on a backup machine. I just checked and all are there. They have file names like: 1658299911.M966551P8821.mail,S=5001,W=5108:2,S 1664572476.M701757P94428.mail,S=4051,W=4135:2,Sab 1665119988.M609674P37848.mail,S=8455,W=8629:2,Sab 1665757235.M137163P32739.mail,S=5838,W=5950:2,S 1665774793.M299412P37846.mail,S=4669,W=4755:2,S 1665782571.M706364P40033.mail,S=12191,W=12379:2,S The backup machine has all the dovecot files for that user. How can I restore those email from the backup machine to the new server? -- Doug

2 1

Can I use a static userdb or no?
by social+17dw1scw＠lombra.net 13 May '26

13 May '26

Hi, I've been researching this for a while now, and can't find a definitive answer. I have a virtual setup, with globally static UID, GID and mail locations set. The documentation is clear that this lets me use a static userdb instead of SQL. But then, doveadm mailbox list -A requires that a valid iterate_query is set, and that requires an SQL userdb. So, which is it? If querying does not work with a static userdb, that seems like a significant caveat. I'm also curious how this works with prefetch. I understand I can make the passdb query return static values, but I figure since I already have those configured, I shouldn't need to do that. How can I determine whether prefetching is working as intended? Thank you.

3 2

postfix/dovecot migration
by Bryan Simmons 13 May '26

13 May '26

Moving postfix and dovecot to a new server including all current users and emails. There exists several dovecot files in each user mail directory: dovecot.index dovecot.index.cache dovecot.index.log dovecot-keywords dovecot.list.index.log dovecot.mailbox.log dovecot-uidlist dovecot-uidvalidity dovecot-uidvalidity.612d3d34 Should these files be migrated also or will dovecot recreate them as needed? Thank you, Bryan

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