00:00:21.879 [REMOVED][27411289] +OK REMOVED is ready and awaiting your commands! Glad to meet you REMOVED! How can I help you? The time now is Mon, 03 Feb 2020 07:00:21 +0000 (UTC) <85caccdd-ee05-47e7-b9a5-2d0c7c47f71a@REMOVED>

00:00:21.879 [REMOVED][27411289] connected at 2/3/2020 12:00:21 AM
00:00:22.171 [REMOVED][27411289] CAPA
00:00:22.171 [REMOVED][27411289] +OK Capability list follows
SASL NTLM
TOP
UIDL
USER
STLS
IMPLEMENTATION Smartertools_SmarterMail
.

00:00:22.492 [REMOVED][27411289] USER REMOVED
00:00:22.492 [REMOVED][27411289] +OK User:'REMOVED' ok
00:00:22.812 [REMOVED][27411289] PASS XXXX
00:00:22.814 [REMOVED][27411289] +OK Password ok

00:00:22.814 [REMOVED][27411289] REMNOVED logged in
00:00:23.131 [REMOVED][27411289] STAT
00:00:23.131 [REMOVED][27411289] +OK 1 44296
00:00:23.367 [REMOVED][27411289] LIST
00:00:23.367 [REMOVED][27411289] +OK 1 messages (44296 octets)

00:00:23.367 [REMOVED][27411289] 1 44296

00:00:23.367 [REMOVED][27411289] .

00:00:23.367 [REMOVED][27411289] list response given with 1 messages.
00:00:23.932 [REMOVED][27411289] UIDL
00:00:23.932 [REMOVED][27411289] +OK 1 messages (44296 octets)

00:00:23.932 [REMOVED][27411289] 1 sm_00000001_8b2692f6b3b74cf39b83a6c752dc6275

00:00:23.932 [REMOVED][27411289] .

00:00:23.932 [REMOVED][27411289] uidl list given for 1 messages
00:00:24.571 [REMOVED][27411289] QUIT
00:00:24.571 [REMOVED][27411289] +OK POP3 server signing off

00:00:24.571 [REMOVED][27411289] disconnected at 2/3/2020 12:00:24 AM

00:07:48.871 [REMOVED][65395878] +OK REMOVED is ready and awaiting your commands! Glad to meet you REMOVED! How can I help you? The time now is Tue, 04 Feb 2020 07:07:48 +0000 (UTC) <6d2d95f3-fb74-46f3-8aa3-b38e56078bb0@REMOVED>

00:07:48.871 [REMOVED][65395878] connected at 2/4/2020 12:07:48 AM
00:07:49.166 [REMOVED][65395878] CAPA
00:07:49.166 [REMOVED][65395878] +OK Capability list follows
SASL NTLM PLAIN
TOP
UIDL
USER
STLS
IMPLEMENTATION Smartertools_SmarterMail
.

00:07:49.486 [REMOVED][65395878] AUTH PLAIN
00:07:49.486 [REMOVED][65395878] 
00:37:53.233 [REMOVED][65395878] -ERR Session timeout, OK POP Server signing off
00:37:53.233 [REMOVED][65395878] -ERR Session timeout, OK POP Server signing off
00:37:53.233 [REMOVED][65395878] disconnected at 2/4/2020 12:37:53 AM

FIXED: Outlook 2007 and base versions of 2010 have issues authenticating via POP.

Connection error: Server bug: non-empty initial PLAIN challenge Host: REMOVED

Hello!

Looks like your server is implementing SASL-PLAIN incorrectly or in a way that your library doesn't like.