diff --git a/ChangeLog b/ChangeLog
index 1978bf8b..2c3e91ab 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -307,6 +307,8 @@ releases.
       (0.10th resp. IPv6 relevant only, amend for gh-1479)
 * config/pathes-freebsd.conf
     - Fixed filenames for apache and nginx log files (gh-1667)
+* filter.d/exim.conf
+    - optional part `(...)` after host-name before `[IP]` (gh-1751)
 * filter.d/sshd.conf
     - new aggressive rules (gh-864):
       - Connection reset by peer (multi-line rule during authorization process)
diff --git a/config/filter.d/exim.conf b/config/filter.d/exim.conf
index 5d293429..a320de52 100644
--- a/config/filter.d/exim.conf
+++ b/config/filter.d/exim.conf
@@ -17,13 +17,13 @@ before = exim-common.conf
 #prefregex = ^%(pid)s <F-CONTENT>\b(?:\w+ authenticator failed|([\w\-]+ )?SMTP (?:(?:call|connection) from|protocol(?: synchronization)? error)|no MAIL in|(?:%(host_info_pre)s\[[^\]]+\]%(host_info_suf)s(?:sender verify fail|rejected RCPT|dropped|AUTH command))).+</F-CONTENT>$
 
 failregex = ^%(pid)s %(host_info)ssender verify fail for <\S+>: (?:Unknown user|Unrouteable address|all relevant MX records point to non-existent hosts)\s*$
-            ^%(pid)s \w+ authenticator failed for (\S+ )?\(\S+\) \[<HOST>\](?::\d+)?(?: I=\[\S+\](:\d+)?)?: 535 Incorrect authentication data( \(set_id=.*\)|: \d+ Time\(s\))?\s*$
+            ^%(pid)s \w+ authenticator failed for (?:[^\[\( ]* )?(?:\(\S*\) )?\[<HOST>\](?::\d+)?(?: I=\[\S+\](:\d+)?)?: 535 Incorrect authentication data( \(set_id=.*\)|: \d+ Time\(s\))?\s*$
             ^%(pid)s %(host_info)srejected RCPT [^@]+@\S+: (?:relay not permitted|Sender verify failed|Unknown user)\s*$
             ^%(pid)s SMTP protocol synchronization error \([^)]*\): rejected (?:connection from|"\S+") %(host_info)s(?:next )?input=".*"\s*$
             ^%(pid)s SMTP call from \S+ %(host_info)sdropped: too many nonmail commands \(last was "\S+"\)\s*$
             ^%(pid)s SMTP protocol error in "AUTH \S*(?: \S*)?" %(host_info)sAUTH command used when not advertised\s*$
-            ^%(pid)s no MAIL in SMTP connection from (?:\S* )?(?:\(\S*\) )?%(host_info)sD=\d+s(?: C=\S*)?\s*$
-            ^%(pid)s ([\w\-]+ )?SMTP connection from (?:\S* )?(?:\(\S*\) )?%(host_info)sclosed by DROP in ACL\s*$
+            ^%(pid)s no MAIL in SMTP connection from (?:[^\[\( ]* )?(?:\(\S*\) )?%(host_info)sD=\d+s(?: C=\S*)?\s*$
+            ^%(pid)s ([\w\-]+ )?SMTP connection from (?:[^\[\( ]* )?(?:\(\S*\) )?%(host_info)sclosed by DROP in ACL\s*$
 
 ignoreregex = 
 
diff --git a/fail2ban/tests/files/logs/exim b/fail2ban/tests/files/logs/exim
index 9053bf8d..44d9e34b 100644
--- a/fail2ban/tests/files/logs/exim
+++ b/fail2ban/tests/files/logs/exim
@@ -67,3 +67,6 @@
 2016-04-01 11:09:21 [18648] SMTP protocol error in "AUTH LOGIN" H=host.example.com (SERVER) [192.0.2.1]:4692 I=[172.89.0.6]:25 AUTH command used when not advertised
 # failJSON: { "time": "2016-03-27T16:48:48", "match": true , "host": "192.0.2.1" }
 2016-03-27 16:48:48 [21478] 1akDqs-0005aQ-9b SMTP connection from host.example.com (SERVER) [192.0.2.1]:47714 I=[172.89.0.6]:25 closed by DROP in ACL
+
+# failJSON: { "time": "2017-04-23T22:45:59", "match": true , "host": "192.0.2.2", "desc": "optional part (...)" }
+2017-04-23 22:45:59 fixed_login authenticator failed for bad.host.example.com [192.0.2.2]:54412 I=[172.89.0.6]:587: 535 Incorrect authentication data (set_id=user@example.com)