Not in psa-horde.log (only failed logins), but yes in /var/log/messages (Once it worked from the telnet try)
/var/log/messages
Nov 21 22:10:42 ns61546 xinetd[14593]: START: poppassd pid=19646 from=::ffff:127.0.0.1
Nov 21 22:10:55 ns61546 xinetd[14593]: EXIT: poppassd status=1 pid=19646 duration=13(sec)
Nov 21 22:10:56 ns61546 xinetd[14593]: START: poppassd pid=19649 from=::ffff:127.0.0.1
Nov 21 22:11:21 ns61546 xinetd[14593]: EXIT: poppassd status=1 pid=19649 duration=25(sec)
Nov 21 22:11:27 ns61546 xinetd[14593]: START: poppassd pid=19696 from=::ffff:127.0.0.1
Nov 21 22:11:49 ns61546 poppassd[19696]: poppassd: changed POP3 password for '
[email protected]'
Nov 21 22:12:01 ns61546 xinetd[14593]: EXIT: poppassd status=0 pid=19696 duration=34(sec)
Nov 21 22:12:03 ns61546 xinetd[14593]: START: poppassd pid=19743 from=::ffff:127.0.0.1
Nov 21 22:12:27 ns61546 xinetd[14593]: EXIT: poppassd status=1 pid=19743 duration=24(sec)
Nov 21 22:12:32 ns61546 xinetd[14593]: START: poppassd pid=19747 from=::ffff:127.0.0.1
Nov 21 22:12:34 ns61546 xinetd[14593]: EXIT: poppassd status=1 pid=19747 duration=2(sec)
Nov 21 22:21:21 ns61546 xinetd[14593]: START: poppassd pid=21532 from=::ffff:127.0.0.1
Nov 21 22:21:21 ns61546 xinetd[14593]: EXIT: poppassd status=1 pid=21532 duration=0(sec)
Nov 21 22:22:02 ns61546 xinetd[14593]: START: poppassd pid=21591 from=::ffff:127.0.0.1
Nov 21 22:22:02 ns61546 xinetd[14593]: EXIT: poppassd status=1 pid=21591 duration=0(sec)
Nov 21 22:23:00 ns61546 xinetd[14593]: START: poppassd pid=21599 from=::ffff:188.165.15.68
Nov 21 22:23:03 ns61546 xinetd[14593]: EXIT: poppassd status=1 pid=21599 duration=3(sec)
Nov 21 22:30:09 ns61546 xinetd[14593]: readjusting service poppassd
Nov 21 22:30:34 ns61546 xinetd[14593]: readjusting service poppassd
tail /var/log/psa-horde/psa-horde.log
[pid 14959 on line 109 of "/usr/share/psa-horde/imp/lib/Imple/SpellChecker.php"]
Nov 21 08:28:36 HORDE [error] [imp] FAILED LOGIN for
[email protected] [x.x.x.70] to {127.0.0.1:143 [imap/notls]} [pid 15876 on line 139 of "/usr/share/psa-horde/imp/lib/Auth/imp.php"]
Nov 21 08:29:51 HORDE [error] [imp] FAILED LOGIN for
[email protected] [x.x.x.70] to {127.0.0.1:143 [imap/notls]} [pid 15877 on line 139 of "/usr/share/psa-horde/imp/lib/Auth/imp.php"]
Nov 21 10:49:43 HORDE [error] [imp] FAILED LOGIN for
[email protected] [x.x.x.70] (forwarded for [172.16.0.3]) to {127.0.0.1:143 [imap/notls]} [pid 15877 on line 139 of "/usr/share/psa-horde/imp/lib/Auth/imp.php"]
Nov 21 10:50:47 HORDE [error] [imp] FAILED LOGIN for
[email protected] [x.x.x.70] (forwarded for [172.16.0.3]) to {127.0.0.1:143 [imap/notls]} [pid 15877 on line 139 of "/usr/share/psa-horde/imp/lib/Auth/imp.php"]
Nov 21 11:24:02 HORDE [error] [imp] spellcheck failed: Error: No word lists can be found for the language "es_ES".
[pid 15878 on line 109 of "/usr/share/psa-horde/imp/lib/Imple/SpellChecker.php"]
Nov 22 09:43:17 HORDE [error] [imp] spellcheck failed: Error: No word lists can be found for the language "es_ES".
[pid 23885 on line 109 of "/usr/share/psa-horde/imp/lib/Imple/SpellChecker.php"]