After upgrading Debian to 11 I found Dovecot at version 2.3.13 (89f716dc2). Now auth method NTLM fails and is not even listed:
# doveadm pw -l SHA1 SSHA512 SCRAM-SHA-256 BLF-CRYPT PLAIN HMAC-MD5 OTP SHA512 SHA DES-CRYPT CRYPT SSHA MD5-CRYPT PLAIN-MD4 PLAIN-MD5 SCRAM-SHA-1 SHA512-CRYPT CLEAR CLEARTEXT ARGON2I ARGON2ID SSHA256 MD5 PBKDF2 SHA256 CRAM-MD5 PLAIN-TRUNC SHA256-CRYPT SMD5 DIGEST-MD5 LDAP-MD5
/var/log/dovecot.log Jan 22 16:20:32 auth: Fatal: Unknown authentication mechanism 'NTLM' Jan 22 16:20:32 master: Error: service(auth): command startup failed, throttling for 2.000 secs Jan 22 16:20:34 auth: Fatal: Unknown authentication mechanism 'NTLM' Jan 22 16:20:34 master: Error: service(auth): command startup failed, throttling for 4.000 secs Jan 22 16:20:38 auth: Fatal: Unknown authentication mechanism 'NTLM' Jan 22 16:20:38 master: Error: service(auth): command startup failed, throttling for 8.000 secs Jan 22 16:20:46 auth: Fatal: Unknown authentication mechanism 'NTLM' Jan 22 16:20:46 master: Error: service(auth): command startup failed, throttling for 16.000 secs
# doveconf -n # 2.3.13 (89f716dc2): /etc/dovecot/dovecot.conf # Pigeonhole version 0.5.13 (cdd19fe3) # OS: Linux 5.10.0-11-amd64 x86_64 Debian 11.2 # Hostname: imail.khmfdbyekekelj1rmytwnfh1bc.dx.internal.cloudapp.net auth_mechanisms = plain login ntlm debug_log_path = /var/log/dovecot-debug.log info_log_path = /var/log/dovecot-info.log log_path = /var/log/dovecot.log maildir_stat_dirs = yes 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 compat { alias_for = hidden = yes inbox = no list = no location = prefix = INBOX. separator = . } 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 Trash { special_use = \Trash } prefix = separator = . } passdb { args = /etc/dovecot/dovecot-sql.conf.ext driver = sql } plugin { mail_plugins = " quota trash sieve" sieve = file:~/sieve;active=~/.dovecot.sieve } protocols = " imap sieve" service auth { unix_listener /var/spool/postfix/private/auth { group = postfix mode = 0666 user = postfix } unix_listener auth-client { mode = 0660 } } service stats { unix_listener stats-reader { group = vmail mode = 0660 user = vmail } unix_listener stats-writer { group = vmail mode = 0660 user = vmail } } ssl_cert =
Regards, David Koski