Hi all!

First of all, I want ti thank the whole Dovecot community (developers for developing and fast responses, users for populating and responses too). Dovecot is a really good and fast IMAP server - it serves near 3000 in our installation.

Now I have a problem and request community's help its resolving;) Dovecot version: 1.0.13, compiled with vpopmail support. I have an account spam@domain.com (:-), in which we put all our spam (we gather statistic later). There can be 10 and more delivery attempts in a second to maildir of this account during the spam attacks on our server. The queue of our server can grow up to 20k messages, and all of these messages are sent to spam@domain.com. I found a lot of such strings in dovecot.log file during such DoS attack:

dovecot.log:deliver(spam@domain.com): May 16 04:18:48 Info: msgid=<01c8b6da$a8bacf80$b7af2abe@sale>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:18:59 Info: msgid=<6611811842.20080516012444@poiusadfhnvxzmdiasdasgkhlsdkfg.com>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:20:06 Info: msgid=<01c8b6a8$7b552e00$a0a4034c@sale>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:20:14 Info: msgid=<360825920.32055246029506@mirgames.ru>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:20:50 Info: msgid=<01c8b6b1$0df9cb00$cc36dfc9@tek2>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:21:00 Info: msgid=<087901c7ca2d$ef272640$1e01a8c0@telefonia.InterCable.net>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:21:01 Info: msgid=<000701c8b6d2$01ff999f$c491aca7@snoueiij>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:22:32 Info: msgid=<000801c8b69b$060c0230$3cd8a4b7@cpbvlrx>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:22:45 Info: msgid=<000801c8b6a5$04ba6412$9910848d@aldldr>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:22:45 Info: msgid=<031401c772e2$adc5be40$1e01a8c0@mtu-net.ru>: save failed to INBOX: Timeout while waiting for lock dovecot.log:deliver(spam@domain.com): May 16 04:23:08 Info: msgid=<01c8b6db$0222fe80$b7af2abe@info>: save failed to INBOX: Timeout while waiting for lock

What can I do for resolving this locks? The queue of my server becomes really big! May be, while looking into uidlist file, can dovecot LDA lock it? And other deliver processes can't open it and wait for him?

$ dovecot --version 1.0.13

dovecot -n

1.0.13: /etc/dovecot.conf

log_path: /var/log/dovecot.log protocols: imap pop3 ssl_disable: yes login_dir: /var/run/dovecot/login login_executable(default): /usr/libexec/dovecot/imap-login login_executable(imap): /usr/libexec/dovecot/imap-login login_executable(pop3): /usr/libexec/dovecot/pop3-login login_greeting: Server is ready. login_process_per_connection: no login_greeting_capability(default): yes login_greeting_capability(imap): yes login_greeting_capability(pop3): no login_max_connections: 1024 first_valid_uid: 39 last_valid_uid: 39 first_valid_gid: 39 last_valid_gid: 39 fsync_disable: yes maildir_copy_with_hardlinks: yes mail_executable(default): /usr/libexec/dovecot/imap mail_executable(imap): /usr/libexec/dovecot/imap mail_executable(pop3): /usr/libexec/dovecot/pop3 mail_plugins(default): quota imap_quota mail_plugins(imap): quota imap_quota mail_plugins(pop3): quota mail_plugin_dir(default): /usr/lib/dovecot/imap mail_plugin_dir(imap): /usr/lib/dovecot/imap mail_plugin_dir(pop3): /usr/lib/dovecot/pop3 auth default: mechanisms: plain login cram-md5 default_realm: tversu.ru cache_size: 10240 user: vpopmail username_format: %Lu passdb: driver: vpopmail args: cache_key=%u dovecot userdb: driver: vpopmail socket: type: listen client: path: /var/spool/postfix/private/auth mode: 438 user: postfix group: postfix master: path: /var/run/dovecot/auth-master mode: 438 plugin: quota: maildir:ignore=Trash

WBR, Mike Grozak, TvSU IC