SMTP and IMAP authentication critically fails out of the blue

[Felix Plapper]

Hello Community and first things First:
dovecot --version2.2.9dovecot -n# 2.2.9: /etc/dovecot/dovecot.conf# OS: Linux 3.13.0-042stab125.5 x86_64 Ubuntu 14.04.5 LTSauth_mechanisms = plain logindict {  sqlquota = mysql:/etc/dovecot/dovecot-dict-sql.conf}listen = *,[::]log_timestamp = "%Y-%m-%d %H:%M:%S "login_log_format_elements = user=<%u> method=%m rip=%r lip=%l mpid=%e %c %kmail_fsync = alwaysmail_home = /var/vmail/%d/%nmail_location = maildir:~/mail_nfs_index = yesmail_nfs_storage = yesmail_plugins = quota aclmanagesieve_notify_capability = mailtomanagesieve_sieve_capability = fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date ihavemmap_disable = yesnamespace {  list = yes  location = maildir:%%h/:INDEXPVT=~/Shared/%%u  prefix = Shared/%%u/  separator = /  subscriptions = yes  type = shared}namespace inbox {  inbox = yes  location =  mailbox Archiv {    special_use = \Archive  }  mailbox Archive {    auto = subscribe    special_use = \Archive  }  mailbox Archives {    special_use = \Archive  }  mailbox "Deleted Messages" {    special_use = \Trash  }  mailbox Drafts {    auto = subscribe    special_use = \Drafts  }  mailbox Entwürfe {    special_use = \Drafts  }  mailbox "Gelöschte Objekte" {    special_use = \Trash  }  mailbox Gesendet {    special_use = \Sent  }  mailbox Junk {    auto = subscribe    special_use = \Junk  }  mailbox Papierkorb {    special_use = \Trash  }  mailbox Sent {    auto = subscribe    special_use = \Sent  }  mailbox "Sent Messages" {    special_use = \Sent  }  mailbox Trash {    auto = subscribe    special_use = \Trash  }  prefix =  separator = /}passdb {  args = /etc/dovecot/dovecot-mysql.conf  driver = sql}plugin {  acl = vfile  acl_anyone = allow  acl_shared_dict = file:/var/vmail/shared-mailboxes.db  quota = dict:User quota::proxy::sqlquota  quota_rule2 = Trash:storage=+100%%  sieve = /var/vmail/sieve/%u.sieve  sieve_after = /var/vmail/sieve/global.sieve  sieve_max_script_size = 1M  sieve_quota_max_scripts = 0  sieve_quota_max_storage = 0}protocols = imap sieve lmtp pop3service auth {  unix_listener /var/spool/postfix/private/auth_dovecot {    group = postfix    mode = 0660    user = postfix  }  unix_listener auth-master {    mode = 0600    user = vmail  }  unix_listener auth-userdb {    mode = 0600    user = vmail  }  user = root}service dict {  unix_listener dict {    group = vmail    mode = 0660    user = vmail  }}service lmtp {  unix_listener /var/spool/postfix/private/dovecot-lmtp {    group = postfix    mode = 0600    user = postfix  }  user = vmail}service managesieve-login {  inet_listener sieve {    port = 4190  }  process_min_avail = 2  service_count = 1  vsz_limit = 128 M}service managesieve {  process_limit = 256}ssl_cert = </etc/ssl/mail/mail.crtssl_cipher_list = EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH:+CAMELLIA256:+AES256:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!ECDSA:CAMELLIA256-SHA:AES256-SHA:CAMELLIA128-SHA:AES128-SHAssl_dh_parameters_length = 2048ssl_key = </etc/ssl/mail/mail.keyssl_protocols = !SSLv3 !SSLv2userdb {  args = /etc/dovecot/dovecot-mysql.conf  driver = sql}protocol imap {  mail_plugins = quota imap_quota imap_acl acl}protocol lmtp {  auth_socket_path = /var/run/dovecot/auth-master  mail_plugins = quota sieve acl  postmaster_address = postmaster at domain1.com}protocol sieve {  managesieve_logout_format = bytes=%i/%o}remote 127.0.0.1 {  disable_plaintext_auth = no}###########################################



Mail.errNov 13 23:59:06 webdev dovecot: auth: Error: PLAIN(account at domain2.com, XXX.XXX.XXX.XXX,<y869CoDETEST4dHk>): Request 29154.1 timed out after 150 secs, state=1###########################################


Mail.logNov 13 23:27:54 webdev dovecot: auth: Error: LOGIN(account at domain1.com,IP.IP.IP.IP,<oN4ly+TestDZ6dHk>): Request 28118.1 timed out after 150 secs, state=1Nov 13 23:27:57 webdev dovecot: auth: Error: PLAIN( account at domain2.com,XXX.XXX.XXX.XXX,<FAxKe+JaatES7tHk>): Request 28120.1 timed out after 150 secs, state=1Nov 13 23:28:24 webdev dovecot: imap-login: Disconnected: Inactivity during authentication (disconnected while authenticating, waited 180 secs): user=<>, method=LOGIN, rip=ClientIP, lip=ServerIP, TLS: Disconnected, TLSv1.2  with cipher DHE-RSA-AES128-GCM-SHA256 (128/128 bits) [...]Nov 13 23:47:15 webdev dovecot: imap-login: Aborted login (no auth attempts in 0 secs): user=<>, rip=84.119.151.17, lip=62.75.185.32###########################################


I did not change anything on my client nor serverside setup and i suddenly could not reach the Mailserver anymore. Obviously I can reach the Server using SSH or HTTP.
I hope I provided all infos you need to help me in this situation. And am grateful for every hint to solve this

Note: Older mailinglist threads did not help because a link which solved a similar case is not available anymore.plus I tried to make the given pieces of information structured using styles. Maybe it gets delivered,displayed and enhances the ease of reading.